Abstract
Toxic contaminants from intense industrial operations are entering wetlands, harming human health and biodiversity. Macrophytes serve as principal producers in aquatic environments including natural wetlands, providing shelter, food, and, most crucially, intricate relationships with the surrounding microbial assemblage for support and microorganisms attachment. Wetlands have been nature's kidneys, for filtering water. Recent research has examined macrophytes' phytoremediation abilities. With recent improvements focused on engineered wetland technology, microbiological characterization, and genetic engineering, phytoremediation strategies have also benefited. However, little research has examined the role surrounding microbial population play on macrophyte efficiency in pollutant degradation, the extent and even mechanisms of these interactions, and their potential utility in wastewater treatment of diverse industrial effluents. Our bid for greener solutions implies that macrophyte-microorganisms’ interspecific interactions for in situ treatment of effluents should be optimised to remove contaminants before discharge in natural waterbodies or for recycle water usage. This review provides for the varied types of plants and microbial interspecific interactions beneficial to effective phytoremediation processes in artificial wetland design as well as considerations and modifications in constructed wetland designs necessary to improve the bioremediation processes. Additionally, the review discusses the latest advancements in genetic engineering techniques that can enhance the effectiveness of phyto-assisted wastewater treatment. We will also explore the potential utilisation of invasive species for their demonstrated ability to remove pollutants in the controlled setting of constructed wetlands.
Similar content being viewed by others
Avoid common mistakes on your manuscript.
1 Introduction
As we face the challenges of environmental pollution, there is a need to develop sustainable remediation approaches and effective strategies for the treatment of industrial effluents brought about by economic developments. Constructed wetlands have emerged as favorable option for bioremediation due to their ecological significance, one major support framework present in all wetlands are the plants (macrophytes) enabled by the interplay of endophytic and rhizospheric dwelling microorganisms that participate in the degradation of compounds including pollutants within the area covered by these plants (Supreeth 2022; Borgulat et al. 2022). Aquatic plants (macrophytes) provide a structure that enhances flocculation and sedimentation, and the conditions for microbial activities to stabilize and degrade pollutants (Kochi et al. 2020). This is possible because the stems, leaves, and roots provide surfaces for microbial adhesion between the soil/silt interphase and the water column (tidal currents). These surfaces provide protection and an environment for the development of microbial communities (Srivastava et al. 2017; Onaebi et al. 2020).
Although found abundantly in aquatic environments, free-living microorganisms are less efficient at sourcing and processing nutrients, than consortia dwelling microorganisms, especially those that live in close proximity to these aquatic plants. This is because concerted enzymes from consortium cooperation are necessary to degrade complex substrates, as such, it is beneficial to reside within groups. Additionally, the type and composition of nutrients present modifies microbial species composition and changes ecological communities as they attempt to adapt to these chemical compounds, which in turn affects ecological system performance. Other environmental pressures that affect microbial fluxes also change microbial communities. Microorganisms need carbon to proliferate and increase enzyme levels (metabolic activities) in any given environment (Gupta et al. 2017; Huang et al. 2020). Studies in bioprospecting have shown that the assimilation of carbon and other essential nutrients necessary for metabolic activities and biomass growth induces cooperation amongst microorganisms, inadvertently leading to the production of important biological products used in industries such as food, medicine, agriculture, water, and energy recovery (Abbas et al. 2021).
Pertinently, these macrophyte-microbe interactions can be found in root organic deposits, in stems and leaves (endophytic), enhanced by varied nutrient contents and the type of fortuitous stem/root-associated microbial communities (Shaikh et al. 2018). The rhizosphere is a narrow zone of soil surrounding aquatic plant roots where root exudates cause biological activity (Clairmont et al. 2019). The rhizosphere attracts bacteria and other microorganisms that feed on decaying root material from sloughed off border cells and mucilage (thick, viscous, high molecular weight, insoluble, polysaccharide-rich material that lubricates roots against desiccation) (Zhalnina et al. 2018). Rhizo-deposition enables microorganisms to grow on roots (Yadav et al. 2015). Root exudates contain sugars, nucleotides, amino acids, organic acids, phenolic compounds, enzymes, phytohormones, and vitamins that can attract or inhibit microorganisms, act as signal molecules in the rhizosphere, and sequester hazardous toxic elements (e.g. cadmium, chromium VI, and others). Chemical components of root exudates may facilitate symbiotic or mutualistic associations, such as N2 fixation and mycorrhizal associations, or deter microorganisms via negative associations, such as competition, pathogenesis, and parasitism among plants (Pathan et al. 2020). Rhizosphere sediment, plants, and microorganisms regulate microbial diversity and dynamics (Olanrewaju et al. 2019). In addition, compounds that are absorbed by the plants, interact with endophytic micoroganisms found within the stem as well as the leaves.
Apart from the macrophyte selection and enhancement of microbial diversity, the removal of industrial pollutants in constructed wetlands involves a combination of physical, chemical, and biological processes. This involves incorporating other strategies such as the constructed wetland design to allow for sufficient contact time between the pollutants and biota and promoting effective biological and chemical processes for the removal of pollutants (Hassan et al. 2021). Considering sedimentation traps and filtrations strips will ensure a consistent flow velocity within the constructed wetland to enable sedimentation of unwanted particles and pollutants and allowing the capture and filtration runoffs to prevent transport of the pollutants further in the wetlands (Mangangka 2013). These strategies, when integrated together will contribute to the effectiveness of constructed wetlands in removing industrial pollutants.
As we progressively look for sustainable approaches to wastewater treatment, our understanding of the phyto-degradation process and the application to phyto-assisted bioremediation must integrate optimization processes to improve the removal of pollutants from contaminated water, with emphasis and consideration placed on ensuring specialized treatments for various industrial wastewaters. Thus, this review intends to present various approaches to consider in integrating phytoremediation within an artificial wetland construction that considers the importance of macrophyte-microorganisms’ interactions in pollutants removal. Further, the review will highlight the broader implications of this approach for environmental management and pioneering the development of innovative and eco-friendly strategies to reduce the challenges posed by industrial pollution.
2 The macrophyte as a micro-ecological system
The rhizosphere food web can be divided into three distinct channels, each with its own energy source: detritus-dependent fungi and bacterial species, and root energy-dependent invertebrates, symbiotic species, and some arthropods. Because the amount of detritus available and the role of root sloughing change as roots grow and age, the food web is constantly in a state of flux. This bacterial channel is considered a faster channel because species can focus on more accessible resources in the rhizosphere and have a faster reproduction rate than fungal channels. The size and distribution of microbial assemblages in this zone are directly related to the system's nutrient resources' quality and quantity. Due to the introduction of exudates and the relationships that they maintain, aquatic plants have an impact on which microbial species in the rhizosphere are selected against. The amount of root exudates that plants can produce has an impact on the rhizosphere's microbial communities (Zhu and Sikora 1995). Cell counts in the root zone are several orders of magnitude higher than in plant-free soil. The microbial community in rhizosphere roots is more diverse, active, and synergistic implying that microbial genes outnumber plant genes in the rhizosphere (Mendes et al. 2013). Most microbial communities adapt quickly to natural perturbations or external nutrition loading (Reddy et al. 2002). This rhizosphere connection is found in semi-arid soils and wetland habitats (Aguirre-Garrido et al. 2012; Hong et al. 2015).
The occurrence of sedimentation stores inorganic and organic nutrients before releasing them back into the water column. Microbial communities in sediments are critical to wetland functions because they play important roles in substance export, regeneration, and biogeochemical cycling (carbon, nitrogen, sulphur, and iron) (Cheung et al. 2018). Plants can grow in water-saturated sediments, making wetlands ecosystems unique. This allows plants to have adventitious roots/rhizomes with aerenchymatous tissues, which improves oxygen transfer via air pressure gradients and passive mechanisms such as diffusion, and creates an oxygenated aqueous layer around root hairs (Allen 1997). Wetlands' perennial or periodic flooding and plant roots create a dual oxic and anoxic environment that encourages aerobic and anaerobic microbial assemblages (De Mandal et al. 2020). Aerobic bacteria thrive in an oxygen-rich environment provided by roots.
An oxygen-deficient environment promotes anaerobic microbes farthest from the roots (Sand-Jensen et al. 1982). Microorganisms in the anoxic hydric zone produce an oxic surface layer, and redox stratification occurs in the oxygen-deficient zone (De Mandal et al. 2020). Oxygen levels at root respiration sites are regulated by open lacunars in stems, roots, and rhizomes. This gaseous space serves as an oxygen conduit from photosynthetic shoot tissue to subsurface tissue, where aerobic processes keep roots absorptive for nutrient uptake (Bedford et al. 1991). The space between the root hairs is populated by anaerobic microorganisms (which grow at a slower rate). The plant rhizosphere is home to significant quantities of culturable microbes that can benefit humanity due to the presence of aerobes and anaerobes that promote fast cycling (rapid use of carbon sources) (Ghermandi et al. 2010). Individual microbes can benefit plants, but when two or more interact, additive and synergistic effects are expected.
Multiple species can play various roles in a rhizosphere ecosystem. Many rhizosphere microorganisms, for example, provide transformed compounds like nitrates for plant absorption and assimilation, which aids crop production (N2 fixation) by increasing soil/silt fertility. Others offer defence against infections and illnesses. The microbes at this site tend to produce pharmaceutical-grade antibodies. Because of root exudates and metabolic products of symbiotic and pathogenic bacteria, much of the nutrient cycling and disease suppression by plant antibodies occurs near the roots. Due to rhizosphere effects, enriched microorganisms near plant roots improve biodegradation of harmful contaminants (Xiong et al. 2021). These contaminants in the root zone are biodegraded by rhizospheric inhabitants. Plants boost bioremediation by increasing microbial populations and soil metabolism. In wetlands, plant microbiota improves plant uptake of mineral and organic substances from substrates, similar to the role played by land plant microbiome (Alegria-Terrazas et al. 2016). Biodegradable peroxidases and laccases are secreted by root tissues and bacteria. Microbial enzymes and biodegradation are activated by root exudates. The presence of oxygen in the rhizosphere promotes oxidative biodegradation by oxygenases. Plants are super-organisms that rely on their microbiome for specialised functions and characteristics. Macrophytes can influence sediment pollutant removal efficiency due to differences in plant and sediment composition and favourable radial oxygen loss (ROL).
It has been observed that Arabidopsis and agricultural crops influence and benefit from the connected rhizosphere microbial community in the terrestrial landscape (Pérez-Jaramillo et al. 2018; Schmidt et al. 2019). Freshwater hydrophyte rhizospheres also have these metabolic interactions. Most studies focus on specific functional groups, such as ammonia-oxidisers (Huang et al. 2016), dentrifiers (Yin et al. 2020), and anammox bacteria (Zhang et al. 2021). In the past, Collins, and colleagues (2004) demonstrated that, while microbes can grow on any surface, the presence of plants affects microbial composition and abundance. Other studies have shown that plant species influence microbial frequency (Qin et al. 2017; Pietrangelo et al. 2018; Fang et al. 2021). This suggests that specific interactions between plants and their host microorganisms have helped them adapt to new environments and dominate various ecosystems. Vymazal (2007) discovered significant differences in microbial diversity in Phragmitis australis and Phalaris arundinacea rhizospheres. Similarly, Kyambadde et al. (2004) proposed that plant morphology influences microbial frequency, citing the instance of Cyperus papyrus which has a larger root surface and microbial density than Miscanthidium violacuum.
Wetland microbial organisation differs from terrestrial microbial organisation due to oxygen diffusion and soil physicochemical changes (De Mandal et al. 2020). Microbial communities increase biomass and enzyme activity in response to nutrient fluxes, influencing biogeochemical processes and nutrient cycles such as carbon, sulphur, nitrogen, and lead, which affect water quality and productivity (Cheung et al. 2018). It is undeniable that anthropogenic activities have permanently altered the hydrosphere, posing a threat to these microbial communities. Lamers et al. (2012) investigated the impact of microbial communities on aquatic plant growth and performance. The findings show that microbe-catalyzed biogeochemical conversions regulate the composition and distribution of wetland vegetation. The nitrogen, sulphur, and iron cycles are among the most notable conversions.
Amongst the various types of macrophytes, emergent macrophytes are the most productive because they can absorb resources from the hydrosphere, and atmosphere (Westlake 1965) as shown in Fig. 1. Their stems and leaves extend above the water's surface enabling carbon fixation and photosynthesis. Macrophytes, unlike terrestrial plants, anchor in submerged, anoxic sediments. Macrophytes provide an additional oxygen source for microorganisms in the rhizoplane (area directly in contact with the root surface) and the rhizosphere (sediment area loosely attached but influenced by the root), promoting aerobic micro-niches in an otherwise anaerobic environment, such as wetland sediment. Interestingly, the sulphate-rich silt found in wetlands, provides anaerobic microorganisms with an enabling environment. These group of microorganisms are very important in elements (including pollutants) removal from the environment. They use varied strategies such as bioabsorption, bioadsorption, bioaccumulation, and biodegradation. These processes are integrated into the cellular machinery and/or biochemical pathways of these microorganisms (Goud et al. 2020).
Furthermore, strong, fibrous stems improve tissue present in macrophytes, which aids in aeration. For example, macrophytes such as Zizania latifolio and Phragmites australis have this structure, allowing them to translocate oxygen and other primary, secondary, and bioactive compounds into the rhizosphere for plant growth (Toyama et al. 2011), thereby establishing an oxygen-rich sediment microenvironment. By regulating N and P fluxes, emerging macrophytes can help to prevent eutrophication of the mainland and coastal regions. Wetland nitrification and denitrification may account for up to 80% of total N removal (Jahangir et al. 2016). Nitrification (the oxidation of ammonia to nitrate) is primarily an aerobic autotrophic process, whereas denitrification (the step-wise conversion of nitrate to nitrogen gas) is primarily an anaerobic process. At the root surface of emergent macrophytes, two opposing conditions for nitrification and denitrification can co-occur, with radical oxygen loss (ROL) providing oxic microniches for nitrification in an anaerobic environment.
3 Macrophytes involvement in interspecific interactions within wetlands
De Mandal et al. (2020), espouse that despite the great strides made in studying the functional and structural components and dynamics of microbial communities in natural wetlands, further research is needed to unravel the microbial "dark matter" and metabolic potential and their functional properties in these rare ecosystems. Compared to terrestrial and aquatic ecosystems, wetland microbial assemblages are understudied. Thus, a more comprehensive understanding of microbial structures and ecological principles governing community organisation is needed. Additionally, Cheung et al. (2018) states that elucidating the complex community structure and kinetics is essential to understanding the microbial diversity that governs wetlands, considering it is a reservoir of untapped secondary bioactive compounds that can be used for bioremediation of pernicious compounds that threaten the ecosystem.
To this end, microbial network analysis conducted by various researchers over the years have helped our understanding by revealing the complex microbial biomes and the functional roles of the various inhabitants of these unique environmental niches. Current wetland co-occurrence networks tend to focus on bacterial and fungal assemblages in salt marshes (Du et al. 2020; Gao et al. 2021; Wang et al. 2023; Zhang et al. 2023). Table 1 shows some of the interspecific relationships within macrophytes’ rhozosphere that have been identified in wetland and aquatic environments.
4 The importance of phyto-assisted degradation of organic pollutants
Organic molecules released into the environment as a result of numerous human actions pose a serious threat to the ecosystem due to their toxicity, hydrophobicity, and resistance to degradation. Organic chemicals like hydrocarbons, polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls, chlorophenols, toluene, benzene, phenols, trinitrotoluene, herbicides, and pesticides impede soil-associated microbial development and metabolic processes even at low concentrations (Sun et al. 2013). These dangerous chemicals are made up of organic chemical compounds (carbon bases) and mixtures that are primarily products or byproducts of industrial operations, chemical manufacturing, and wastes that are resistant to external degradation via biological methods. Humans are extremely vulnerable to these pollutants (Karaś et al. 2021). The pollution of aquatic environments by organic compounds is regarded as a critical issue because it affects biodiversity, depletes aquatic systems and devastates the environment. Furthermore, due to their toxicity, they can enter the food chain and cause genotoxicity and carcinogenic effects in both animals and humans (Nanseu-Njiki et al. 2010).
Conventional physiochemical approaches to cleaning up organic contaminants from water can be difficult, expensive, and environmentally damaging (Marques et al. 2011). Phytoremediation, or the use of plants to decontaminate polluted water, has gained popularity and is regarded as an effective, inexpensive, and environmentally friendly technique. Nonetheless, plants suited for phytoremediation must become acclimated to contaminated surroundings. However, the existence of organic contaminants tends to inhibit plant growth and, ultimately, the performance of phytoremediation (Thion et al. 2013). The implication is that optimisation and strategies need to be employed for effective bioremediation to be achieved using plants. Recent advances in environmental protection have shown that a combination system of microbes and plants can effectively clean up pollutants. When appropriate plants and microorganisms are introduced into a nutritionally deficient but contaminant-rich ecosystem ( as shown in Fig. 1), the plants interact through the rhizosphere and the roots, the microorganisms form a symbiotic relationship necessary for survival in such adverse conditions. Plants emit compounds that invite microbes to interact. This association causes increased germination and root elongation, resulting in increased pollutant degradation in both the rhizosphere and the phyllosphere (Supreeth 2022). Plant-associated bacteria can alter these compounds through metabolic and enzymatic processes, enhancing the efficacy of phytoremediation (Zhu et al. 2016). Plant-associated bacteria include endophytic, phyllospheric, and rhizospheric bacteria. Although, endophytic bacteria appear to be the best option for improving phytoremediation (Karaś et al. 2021). This is due to their ability to stimulate growth, activate defence system, and boost plant tolerance to organic pollutants (Ma et al. 2015).
5 Endophytes assisted phytoremediation of hydrocarbons
Many endophytic bacteria not only aid in plant development but also improve the elimination of organic contaminants, lowering plant toxicity. Horizontal genes transfer (HGT) has been determined to be the primary mechanism by which bacteria acquire novel capabilities, allowing them to respond quickly to environmental changes (Wang et al. 2010). Once the native population of endophytes acquire these new genes, they are able to tolerate and even proliferate with the new ability to degrade these organic pollutants (Afzal et al. 2014). Moreover, HGT enables the formation of endophytes with heterologous gene expression and novel catabolic pathways, particularly with interconnected species donors and recipients (Hardoim et al. 2008). Azadi and Shojaei (2020) discovered that Pseudomonas sp. has genes that enable it to degrade nearly all PAHs with fewer than four aromatic rings. Zhu and colleagues (2016) used two endophytes (Pseudomonas sp. P-3 and Stenotrophomonas sp. P-1) to degrade PAHs into simpler molecules.
Previously, Burkholderia phytofirmans PSJN, was discovered as an endophytic bacterial strain that colonises a wide range of plants, enhancing their growth. The genome of this bacterium is made up of two chromosomes and one plasmid, which contain genes that encode breakdown processes for a wide range of complex organic substances. This bacterium contains genes that code for aliphatic chemical degrading enzymes such as alkane monooxygenase (alkB) and cytochrome P450 hydroxylase. B. phytofirmans PSJN's genome also contains 15 genes that encode for dioxygenases enzymes. These enzymes are involved in the aromatic ring fission process. Furthermore, this strain's genome contains an astonishing number of GST genes (24 copies). These genes are components of the operons responsible for the breakdown of aromatic chemicals (Mitter et al. 2013). Similarly, Burkholderia cepacia FX2 is a toluene-degrading endophyte that carries a plasmid containing a gene encoding catechol 2,3-dioxygenase, an enzyme important in the degradation of monocyclic aromatic hydrocarbons (Wang et al. 2010).
Endophytic fungi can also be used to manage organic pollutants in the environment. There has been some significant research on the elimination of specific homologous groupings or chemical types in this field (Garnica-Vergara et al. 2016). Endophytic fungi can improve host health and competitiveness by increasing germination and growth rates and improving nutritional element absorption (Aly et al. 2011). In comparison to endophytic bacteria, fungi endophytes are incapable of being primary organic contaminant degraders (Etesami 2018). For example, endophytic Phomopsis liquidambari cannot survive on phenolic 4- hydroxybenzoic acid as its sole source of carbon and energy, but it can efficiently degrade polycyclic aromatic hydrocarbons. This endophytic fungus can also degrade N-heterocyclic chemicals such as indole (Chen et al. 2013). Table 2 shows some endophyte assisted phytoremediation of organic pollutants.
6 Rhizobacteria assisted phytoremediation of hydrocarbons
Rhizoremediation has gained acceptance among scientists because plant roots provide a rich environment for bacteria to thrive at the expense of root exudates; bacteria then act as biocatalysts, removing contaminants, particularly around surrounding sediments (Correa-Garcia et al. 2018). Pollutant-degrading rhizobacteria are regarded as plant-growth promoting rhizobacteria (PGPR), in their absence such pollutants would have inhibited plant development. The removal of these inhibitory compounds would help the plant grow (Kanaly and Harayama 2010). Several effective methods for increasing bacterial breakdown efficiency and resistance to pollutants have been developed. PGPR has been demonstrated to increase organic pollutants removal leading to plant germination improvement and survival in severely polluted areas and accelerating root growth and root biomass accumulation (Huang et al. 2004).
Although, ethylene is required for plant growth, but excessive ethylene caused by stress may inhibit growth (Deikman 1997). Remarkably, PGPR stimulate plant development by consuming amino-cyclopropane carboxylic acid (ACC), an immediate precursor to ethylene, and producing 1-aminocyclopropane-1-carboxylate (ACC) deaminase to reduce ethylene secretions in stressed plant (Safronova et al. 2006). Table 3 provides examples of PGPR that have demonstrated abilities to assist and promote organic pollutant degradation.
7 The importance of phyto-assisted degradation of inorganic pollutants
The most prevalent types of pollutants in wetlands are inorganic (toxic elements). These various inorganic contaminants can persist in nature for longer periods of time and travel over long distances with more effectiveness particularly in aquatic environments. Industries have routinely used several aquatic ecological systems as a discharge point for their wastes. Agricultural and domestic pollution are also significant contributors to the production of inorganic contaminants. These toxic elements pollute both surface and groundwater. Inorganic contaminants can accumulate to lethal levels for humans and biological ecological systems. Toxic elements such as chromium, arsenic, zinc, mercury, lead, and nickel are extremely hazardous to humans, plants, and animals, as well as soil fertility. According to Akram et al. (2018), these toxic elements are common in wetlands and their concentrations are quite high due to bioaccumulation. These metal contaminants concentrations tend to rise in living systems because their retention rates are higher than their discharge rates.
Many inorganic pollutants exist in smaller quantities than other pollutants but garner a lot of attention due to their extremely harmful nature. Such trace element emissions pose serious health risks to humans, and these pollutants enter our bodies via the food chain. Inorganic contaminants continue to pique the interest of environmental chemists. They are typically found in minute concentrations in natural waterways, but some are extremely dangerous even at very low concentrations (Hamelink et al. 1994). Metals such as arsenic (As), lead (Pb), cadmium (Cd), nickel (Ni), mercury (Hg), chromium (Cr), cobalt (Co), zinc (Zn), and selenium (Se) are extremely toxic even in trace amounts. Carcinogens will usually contain some forms of toxic elements and dyes; endocrine disruptors containing these varied inorganic elements in different concentrations can also be found hormones, medications, cosmetics, and personal care products. They are discharged either in active forms or as wastes into aquatic environments. Consequently, the direct discharge of metal-containing effluents into water sources, toxic elements is prevalent in the environment. Humans consume these metals through their food and drinking water. Although, some toxic elements, such as cobalt, copper, iron, manganese, vanadium, and zinc, are essential elements that the body requires in trace amounts for various biochemical systems. Most of these toxic elements have serious health consequences on a wide range of human organs, including eye, nose, skin, and internal organs where they cause headaches, irritations, discomfort, diarrhoea, hematemesis, vomiting, cirrhosis, necrosis, low blood pressure, hypertension, and gastrointestinal distress (Verma et al. 2017).
Arsenic poisoning from contaminated water causes lung, liver, and bladder cancer. Cadmium contamination in water can harm the kidneys and lungs and cause bone fragility. Lead consumption, in particular, has a devastating effect. It has the potential to cause brain and kidney damage. A small amount of lead can disrupt children's learning by causing memory loss, impaired reaction functions, and aggressive behaviour (Sun et al. 2017). Pregnant women may experience miscarriage as a result of increased lead consumption, and it also inhibits sperm production in males. Mercury is also considered a global pollutant because it is widely used for a variety of purposes, and as a result, it has a wide range of negative health effects. Mercury enters the body through blood vessels and exits through urination and scat. It causes a variety of side effects, including loss of peripheral vision, impaired movement coordination, muscle weakness, and speech and hearing impairment (Marques et al. 2011).
However, it is possible to remove these toxic elements from water using a variety of phytoremediation techniques. Aquatic macrophytes like Hydrilla verticillata and Elodea canadensis have been shown to accumulate large amounts of Cd in their tissues from contaminated sediments (Sood et al. 2011). Although, due to three major constraints: low macrophyte biomass, restricted root development, and limited metal extraction, the effectiveness of phytoremediation is insufficient to be commercially viable (Muehe et al. 2015). Therefore, rhizosphere bacteria, particularly those with metal resistance and plant growth-promoting abilities, have received a lot of attention for their ability to improve the efficacy of phytoremediation (Rezania et al. 2016).
8 Endophytes assisted phytoremediation of toxic elements
Currently, the majority of putative endophytic bacteria with hazardous metal resistance have mostly been identified in plant roots. Endophytes like Bacillus sp. Pseudomonas sp. and Achromobacter sp. can help plants extract mixed heavy metal contaminants, as Babu et al. (2013) demonstrated when they isolated a Bacillus thuringiensis strain from the roots of Pinus sylvestris. This strain, known as GSB-1, produced phytohormones that stimulate plant growth while also hastening the removal of potentially hazardous metals from mining tailings. For example, chlorophyll content, biomass output, and heavy metal abstraction (e.g. Cu, As, Ni, Zn, and Pb) in plant seedlings increased after GSB-1 co-cultivation. Arthrobacter and Microbacterium strains colonised the intercellular gaps of root and leaf epidermal tissues extensively, according to Visioli et al. (2015). Furthermore, when compared to other isolates, these endophytes showed excellent plant growth promoting properties. Inoculation using a consortium seemingly improved phytoextraction, translocation, and removal of mixed metals (Fe, Ni, Cu, and Co) from soil. Moreover, endophytic fungi have been extensively studied for their ability to reduce metal toxicity and increase phytoremediation efficiency (Deng and Cao 2017). Some examples of endophytes-assisted phytoremediation for inorganic contaminants is shown in Table 4.
9 Rhizobacteria assisted phytoremediation of toxic elements
The microbial population of the rhizosphere may directly drive root development, promoting plant growth, heavy metal tolerance, and plant fitness (Fasani et al. 2018). Plant growth-promoting rhizobacteria (PGPR) have been discovered to have a high potential for improving the efficacy of phytoremediation. Plant growth and fitness can be enhanced by PGPR, which can also protect plants from infections, increase plant tolerance to toxic elements, improve plant nutrient and heavy metal absorption, as well as aid in translocation. This is accomplished through the production of various chemicals, such as organic acids, siderophores, antibiotics, enzymes, and phytohormones (Ma et al. 2011).
PGPR can synthesise the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which degrades the ethylene precursor ACC. PGPR can help plants grow by producing ACC deaminase, which reduces ethylene synthesis (Glick 2014). Plants inoculated with PGPR containing ACC deaminase produced more biomass, as evidenced by increased root, and shoot densities, resulting in greater heavy metal absorption and phytoremediation effectiveness (Arshad et al. 2007). Furthermore, PGPR can produce bacterial auxin, indole-3-acetic acid (IAA) to promote lateral root initiation and root hair production, thereby increasing plant growth and assisting in phytoremediation (DalCorso et al. 2019). Arbuscular mycorrhizal fungus (AMF) is another important microbial community that may aid plants in phytoremediation. AMF in rhizospheres increases water and nutrient absorption as well as heavy metal bioavailability by increasing the absorptive surface area of plant roots via the large hyphal network (Göhre and Paszkowski 2006). Arbuscular mycorrhizal fungi secrete phytohormones that stimulate plant growth and aid in phytoremediation (Vamerali et al. 2010).
The phyto-bacteria system has been shown to be more efficient than its components at removing toxic elements. Many different microbial communities, according to Dell'Amico et al. (2005), can withstand high heavy metal concentrations when living in rhizosphere soils and rhizoplanes. As molecular biology advances, genetically modified rhizobacteria with pollution degradation genes are being developed to carry out rhizospheric bioremediation. Mercury is considered the most dangerous heavy metal in the environment. Mercury biotransformation by bacteria is reliant on the expression of mer genes cloned from mercury-resistant bacteria. Caprivoidis metallidurans NSR33 is a candidate broad-spectrum mercury resistant recombinant bacterial strain that has been touted for its ability to degrade mercury in wastewater. Researchers were able to create a bacterial strain with two large plasmids (pMOL28 and Pmol30) housed in a meR7ADLF operon using recombinant DNA technology. The plasmids exhibit lower levels of resistance to mercury when isolated; however, when fused together, broad-spectrum mercury resistance is achieved (Rojas et al. 2011). Similarly, recent efforts to eliminate arsenic from the environment have focused on developing genetically modified organisms (GMOs) capable of degrading arsenic at maximum levels in the shortest amount of time. Recent studies show that microbial flora removed 2.2 – 4.5 percent of volatile arsenic after 30 days of treatment; thus, genetic engineering (GE) can be used to improve arsenic volatilization and removal efficiency. Cloning an arsM gene isolated from Sphingomonas desiccabilis and Bacillus idriensis into Escherichia coli in comparison to the wild microbial strain results in a tenfold increase in volatile methylated arsenic gas extrusion (Chen et al. 2013). Huang et al. (2016) recently modified a strain of bacteria, Pseudomonas aureginosa strain Pse-W, which has high Cd2+ resistance and Cd2+ remediation ability. Following the adsorption of metallothioneins to the cell surface of the bacterial strain to attract Cd, the engineered strain demonstrated a significant ability to mobilise Cd. The results showed that inoculating the strain Pse-W increased Cd uptake in plant organs. The study demonstrated that Cd-contaminated fields can be realistically bioremediated more easily by the GE Pseudomonas strain than by wild strains. Table 5 shows examples of integrated PGPR bioremediation of toxic elements.
10 Considerations to improve phytoremediation efficiency in artificial wetlands
In the preceding sections of this review, a variety of plants, endophytes, plant-growth promoting rhizobacteria were presented. It is acknowledged that constructed wetland environments necessitate a diverse range of plant species. The choice of vegetation is predicated on the effluent type and composition that are to be treated. Additionally, when designing constructed wetlands, the efficiency of the bioremediation program may be impacted by the following factors that must be taken into account when determining the suitable plants and phytodegradation activity.
10.1 Bioavailability and element mobility
Chemical composition and sorption characteristics of soil/sediments affect metal mobility and bioavailability (Kos et al. 2012). Toxic metal bioavailability affects phytoextraction's efficacy. For example, low bioavailability limits Pb phytoextraction (Ali et al. 2013). Due to toxic metals' strong binding to soil/sediment particles or precipitation, a large percentage of them are non-bioavailable and inaccessible to phytoremediating plants (Sheoran et al. 2011). Consequently, they remain persistent in the affected soil. Toxic metals in soils can be divided into three bioavailability groups: readily bioavailable (Cd, Ni, Zn, As, Se, and Cu); moderately bioavailable (Co, Mn, and Fe); and least bioavailable (Pb, Cr, and U) (Prasad 2003).
Interestingly, plants like Poaceae species secrete metal-mobilizing "phytosiderophores" into the rhizosphere (Reichman and Parker 2005) to solubilize toxic elements in soil. Natural and induced phytoextraction depend on plant bioaccumulation. Natural phytoextraction uses natural hyperaccumulators with a high metal-accumulating capacity and metal-tolerance (Baker et al. 2000). Induced phytoextraction involves adding a chelator or other chemical to the soil to promote metal solubility or mobilisation, allowing plants to absorb more metals. Metal phytoextraction's low bioavailability is mitigated by the discovery that chelate can increase metal translocation from soil to plants (Blaylock et al. 1999). Soil parameters and chelate type determine bioavailable metals in the soil matrix (Shen and Shi 2005). Increasing heavy metal bioavailability improves phytoextraction with the implication that toxic elements cannot bioaccumulate in such soil. Only a small percentage of soil toxic elements are soluble and absorbable by plants (Blaylock et al. 1999). Zinc and copper are plant-bioavailable toxic elements (Lasat 1999). Low bioavailability of toxic elements like Pb makes phytoextraction less effective (Wang et al. 2006). It is also possible to introduce organisms such as Aspergillus, Penicillium, Gliocladium sp. and Candida sp. into artificial wetlands to produce citric and gluconic acids which are known chelating agents (RoyChowdhury et al. 2018) which will increase bioavailability for phytoextraction.
A plant can increase metal bioavailability in many ways. Root exudates reduce soil pH, which encourages heavy metal desorption from insoluble complexes to generate free ions, raising soil heavy metal concentrations (Thangavel and Subbhuraam 2004). Plants can produce metal-mobilizing chemicals in the rhizosphere, such as phytosiderophores, carboxylates, and organic acids, which alter soil physicochemical characteristics and allow heavy metal chelation, enhancing solubility, mobility, and bioavailability (Padmavathiamma and Li 2012). Rhizosphere microorganisms increase plant heavy metal availability and absorption (Vamerali et al. 2010; Sheoran et al. 2011). These microbes release enzymes and chelates into the rhizosphere, improving heavy metal absorption and translocation (Clemens et al. 2002). PGPR and plant growth promoting endophytes (PGPE) can improve the solubility of water-insoluble Zn, Ni, and Cu by secreting protons or organic anions (Becerra-Castro et al. 2011). PGPR release biosurfactants and siderophores to mobilise toxic elements. Siderophores, which chelate Fe3+, also bind Cd, Ni, As, and Pb (Schalk et al. 2011). Chelating with toxic elements improves siderophore bioavailability to rhizobacteria and plants. In general, rhizobacteria are effective at making heavy metal ions accessible.
Endophytes aid plant Fe2+ uptake by producing low-molecular-weight (500–1500 Da) polar molecules. Endophytic siderophores bind Fe2+ and other bivalent metal ions. They help plants extract additional metal ions from soil and alleviate stress from excessive metal enrichment. They also help plants absorb Fe2+ in Fe2+ deficiency situations, improving plant health and growth.
10.2 Biostimulation (Nutrient supplementation)
Industrial effluents characteristically contain toxic elements and are devoid of growth nutrients and other essential elements. Diluting effluents to levels that living cells can tolerate promotes assimilation, but this strategy does not address the lack of nutrients needed to increase biomass and boost bioremediation efficiency. Apart from adding the major nutrients such C, H, N, O, S, and P; it is also important to encourage certain microbial interactions to provide for some of the essential nutrients or improve the bioassimilation from the environment. In situ bioremediation of metal-polluted effluents may benefit from the introduction and selected mixture of organic wastewater to improve nutrient content and promote growth. Plant-associated microbes boost plant growth in metal-polluted areas, regulate metal absorption and translocation, and increase metal bioavailability by secreting ligands and organic acids (Ma et al. 2016). Few studies have examined the bacterial communities associated with wetland plants, and even fewer have explained their reactions to mixed and contaminated settings (Syranidou et al. 2018). There are few data on how contaminants affect wetland plants' endophytic bacteria. Pollution type and quantity, plant species, biostimulating bacteria administration, or a multifactor combination may affect phytoremediation capacity and underlying endophytic assemblages. Previous research found that inoculating Juncus acutus with an endophytic bacterial consortium eliminated emerging pollutants and metals faster and more effectively than non-inoculated plants (Syranidou et al. 2016).
Whiting et al. (2001) found rhizosphere bacteria may mobilise zinc for T. caerulescens hyperaccumulation. Rhizosphere microflora increases water-soluble zinc in soils, allowing T. caerulescens to accumulate more zinc. When Microbacterium saperdae, Pseudomonas monteilii, and Enterobacter cancerogens were added to surface-sterilized T. caerulescens seeds in autoclaved soil, the zinc content in the shoots doubled over the axenic control. Another finding was that the concentration of selenium (Se) in sediment decreases as the flow channel in the wetland system descends. According to Zhang et al. (1997), carbon content is an essential factor controlling Se distribution in sediment, but dissolved Se input significantly affects this connection, showing that rhizosphere bacteria play an indirect role in metal bioaccumulation. PGP bacteria produce siderophores, which bind metals and increase their bioavailability in the rhizosphere (Gadd 2010). Siderophores are produced by a wide range of microorganisms, but they are more prevalent among PGP bacteria, which grow and produce siderophores best in harsh environmental conditions such as nutrient shortage or high heavy metal concentrations (Rajkumar et al. 2010). P. aeruginosa siderophores increased the concentration of Pb and Cr in the rhizosphere, making them available for maize absorption.
Moreover, PGPR bacteria produce low molecular weight organic acids like gluconic, oxalic, and citric, which aid heavy metal mobilisation and solubility. These organic acids help complex toxic elements, allowing plants to absorb them more easily (Ullah et al. 2015). Gluconacetobacter diazotrophicus can produce 5-ketogluconic acid, a gluconic acid derivative that solubilizes Zn compounds. PGP bacteria produce biosurfactants that boost metal mobilisation and phytoremediation. Microbe-produced biosurfactants form complexes with toxic elements at the soil interface, desorbing metals and increasing solubility and bioavailability (Rajkumar et al. 2012). Juwarkar et al. (2007) mobilised Pb and Cd using Pseudomonas aeruginosa BS2 biosurfactants. Heavy metal stress activates phytochelatein (PC) synthase, produced by certain bacteria. These enzymes bind to toxic elements, especially Cd, via thiolate complexes, increasing metal mobility and availability (Kang et al. 2007).
Heavy metal detoxification must precede phytoremediation (Thakur et al. 2016). Plants often avoid or tolerate heavy metal toxicity. Plants use one of two strategies to keep heavy metal concentrations below toxicity levels (Hall 2002). Microorganisms influence metal mobility, toxicity, and bioavailability. Although, there are significant research on the microbial detoxification processes, there remains aspects that are poorly understood. Understanding the microbial mechanisms that control metal removal in wetlands can improve their long-term efficacy (Kosolapov et al. 2004).
10.3 Bioaugmentation
Bioaugmentation improves an existing microbial population by adding cultivated, sometimes specialised microorganisms (Kurniawan et al. 2022). Bioaugmentation is available in many forms. Current and historical information about contaminated places influences strategy selection. Some contaminants are recalcitrant, requiring two or more bioaugmentation approaches for complete removal. Nwankwegu et al. (2022) described some bioaugmentation types. For example, indigenous microorganisms or the use of exogenous microorganisms (either pure cultures of recognised microorganism species or strains or a collection of distinct microorganisms to build a high-density cell mass called a microbial consortium) to increase cell density, and the use of genetically altered microbes (recombinant microbes). Microorganisms are chosen based on their ability to break down contaminants and withstand various environmental conditions. It is known that bacteria, fungus, yeast, actinomycetes, and algae can survive in a variety of environments and remove toxic elements from polluted areas (Purwanti et al. 2018).
Bioaugmentation by introducing indigenous and exogenous microbes that can tolerate and minimise heavy metal effects is a well-known method of remediating heavy metal contamination (Purwanti et al. 2020). Several studies showed that bioaugmentation is more suitable for treating heavy metal-containing wastewater because the formed stable metal can be quickly separated from the wastewater by accumulating it at the bottom of the treatment area, resulting in complete separation between phases (water and metal) (Shahid et al. 2020) allowing for the introduction of specialised microorganisms.
Additionally, some studies have demonstrated bioaugmentation's effectiveness in treating heavy metal-polluted soil, but its practicality in real-world applications is questioned (Kurniawan et al. 2022). Recent studies found that bioaugmentation degraded pollutants in > 90% of organically damaged environments (Dalecka et al. 2021; Muhamad et al. 2021). However, most of the protocols were executed under controlled laboratory conditions using simulated organic pollutants. Concerns were raised about the application of these approaches in real-scale contaminated sites, specifically the separation of accumulated metal from soil, to create a remediated clean medium free of hazardous toxic elements (Purwanti et al. 2019). These challenges can easily be addressed by constructing prototypes and monitoring trends over a period of time. However, the major obstacle remains cost, as ideal prototype test sizes are relatively expensive to construct.
Other pertinent issues that need consideration include the problem of exogenous microorganisms’ population decrease after being introduced, due to the rigorous adaptation necessitated in the new environment. Environmental and biotic challenges can destroy imported species. Abiotic stressors include temperature, water, pH, nutrient, and pollutant variations (Steinle et al. 2000). Other challenges include competition for limited resources from native species and antagonistic interactions like antibiotic synthesis by competitive organisms and predation by protozoa and bacteriophages. Getting inoculant to the right place can be difficult (Dong et al. 2002). Distribution of microorganisms often rely on mechanical processes. Fungi, proliferation and distribution are usually limited to surface applications, while bacteria can adapt to subsurface or surface uses (Nwankwegu et al. 2022). Therefore, upscale artificially constructed wetlands must consider these challenges within the design.
In summary, considerations to ensure successful bioaugmentation regimes must include prior comprehensive understanding of specific physico-chemical properties of the bioprocess that are linked to poor bioreactor performance, such as: (i) an understanding of the ecological foundation of the microorganisms; (ii) developing techniques for monitoring successional patterns and interspecific interactions within the consortia; (iii) developing a flexible selection criteria; (iv) developing an inoculation strategy; (vi) developing a strategy where necessary for specific gene transfers; and (v) evolving operational and plant management strategies to tackle various challenges as they arise.
10.4 Genetically modified plants and invasive species
Over the years, advances in genetic engineering practise have made it possible to transfer desirable genes to plant species for the phytoremediation process. One of the primary goals of transforming plants with exogenous DNA is to improve heavy metal tolerance and accumulation (Rascio and Navari-Izzo 2011). A candidate macrophyte for phytoremediation must have several characteristics, including a) high biomass production that is adapted to the local and target environment, b) rapid growth, and c) a well-defined transformation protocol.
Plant genetic modification aims to increase the expression of genes encoding uptake, translocation, heavy metal sequestration, and antioxidant activity (Das et al. 2016). According to research, the relationship between antioxidant activity and heavy metal tolerance is directly proportional, as the presence of toxic elements triggers the synthesis of ROS, which causes oxidative stress. Increasing heavy metal tolerance will thus necessitate a strategy to boost antioxidant activity, which can be accomplished by inserting genes that constitutively express the antioxidant machinery (Kozminska et al. 2018). It is technically preferable to modify fast-growing, high biomass plants to increase heavy metal tolerance and uptake rather than forcing hyperaccumulators to increase biomass production. Although hyperacumulators are excellent candidates for phytoremediation, the vast majority are low biomass plants. It is now possible to insert the necessary genes or hyperaccumulation traits into high biomass producing plants using genetic engineering methodologies.
Plant genes that encode heavy metal transporters are typically represented by large gene families. They are potential candidate genes for transformation toward improved phytoremediation potential. Manipulation entails increasing metal accumulation in either the roots or the shoots for phytostabilization or phytoextraction. A plant's biomass production and bioconcentration efficiency are two factors that contribute to its efficiency as a phytoextractor (bioconcentration is the ratio between the concentration of the contaminant in the harvestable parts of the plant and its concentration in the soil). To improve heavy metal accumulation, genes encoding heavy metal/metalloid transporters can be transferred and overexpressed in target plants. Metal ion transporters such as ZIP, MTP, MATE, and HMA family members can be engineered using metallothionein, phytochelatins, and metal chelators genes. These metal chelators function as metal-binding ligands, assisting in heavy metal uptake and root-to-shoot translocation, and controlling the intracellular movement of heavy metal ions in organelles. Heavy metal uptake and translocation can be improved by overexpression of genes encoding natural chelators (Wu et al. 2010). Clemens et al (1999) conducted one of the first studies in this area, screening for plant genes involved in the mediation of metal tolerance, specifically finding the gene for cadmium tolerance, and then applying recombinant technologies to Arabidopsis and S. pombe genes to increase metal tolerance. This method has been replicated in several studies to date (Zhu et al. 2021; Kumar et al. 2019; Qiao et al. 2019).
Although genetic engineering of wetland plants has promising prospects for improving plant performance in heavy metal phytoremediation, the technology has several drawbacks. Higher order organisms are frequently composed of many genes that encode one trait; similarly, mechanisms of heavy metal detoxification and accumulation involve a number of genes. Therefore, it becomes costly and time consuming to try and manipulate multiple genes to enhance the desired traits, with most studies failing. Furthermore, serious ethical concerns limit the use of G-E in phytoremediation research. As a result, field studies may be impractical, particularly for natural wetlands. The introduction of foreign (exogenous) DNA into a system can alter wetland dynamics. Because of its genetic advantage, an invasive species with foreign DNA would compete for resources with native species and eventually take over. As a direct consequence, obtaining approval for field testing in some areas may be difficult, the legitimate concern being the cascading effect on the food chain and ecosystem safety. The same argument can be made for alien species, though their proliferation has increased in the last decade, and some authors have demonstrated their capabilities in metal sequestration, as shown in Table 6. Although, the categorisation of plants as invasive is subjective and country-based, and it is often linked to the adjudged danger it poses to the natural biodiversity and the competitive advantage such alien species may pose to indigenous plants that could lead to possible extinction. Nonetheless, once these invasive species are present they tend to be very difficult to eradicate, thus some researchers have now investigated these alien species for possible utility within these new environments. Table 6 focuses on invasive species identified mainly in South Africa. We consider these species as useful for in situ bioremediation programs where they can be cultivated in a controlled environments and disposed-off using incineration or as feedstock in biogas digesters. This will prevent escape into natural water bodies.
10.5 Artificial wetland constructions
Constructed wetlands (CWs) are engineered systems that are designed and developed to mimic naturally occurring wetland processes (Stefanakis et al. 2014). CWs tend to have one major feature that differentiate them from conventional wastewater treatment facilities: this is the addition of large wetland plants, which include angiosperms and ferns, aquatic mosses, and large algae with easily observable tissues and are collectively known as macrophytes (Omandi and Navalia 2020). These macrophytes proliferate on beds filled with appropriate substrate, mostly in the form of natural media sand and gravel, allowing plants to develop an intricate root system that can penetrate and coalesce (Sehar and Nasser 2019) as shown in Fig. 2. The aquatic plants are grouped together based on their associated microbial assemblages (Hassani et al. 2018; Clairmont et al. 2019; Chowdhury et al. 2020; Deutsch et al. 2021).
It is possible at the storage area for untreated effluent to implement biostimulation (nutrient supplementation) to promote the growth of microorganisms that benefit from the essential nutrients addition when the untreated effluent is deficient in these nutrients. The sand and gravel act as stabilizers and adhesion surfaces. The choice of plant can factor the type and composition of effluent, where effluents is observed to contain metals that are not readily soluble of biologically available, chelating agents may be added or endophytic siderophores to enhance mobility and absorption leading to removal of metals. Plants may be removed in time, once, they have reached absorption capacity and can no longer uptake metals or have died due to the toxicity. These plants can be destroyed and replaced with fresh plants. The same can be done with invasive and genetically modified plants as the space is confined and plant growth can be controlled.
Constructed wetlands were initially employed in the treatment of domestic wastewater (Saleh et al. 2015); however, in recent years, the potential has been expanded to include industrial wastewater (Kaushal et al. 2018), storm-water runoff (Guo et al. 2014), agricultural wastewaters (Wang et al. 2018), and landfill leachate (Madera-Parra and Ríos 2017). Because of the higher concentration of pollutants in the influents, the use of CWs for industrial wastewater treatment remains difficult (Stefanakis 2018). Through a series of processes and mechanisms, CWs with macrophyte plant roots, aquatic microbial communities, and supporting mineral matter are effective at removing various pollutants present in wastewater such as nitrogen, phosphorus, and organic matter (Stefanakis et al. 2014). Advances in phytoremediation using CWs have focused on the remediation of various organic micro-pollutants, such as phenolic compounds (Omandi and Navalia 2020), as well as inorganics from pharmaceuticals, such as endocrine disrupting chemicals (EDCs) and toxic elements (Daley and Kucera 2014). The adaptation of this treatment technology has gained interest around the world, particularly in economically underdeveloped countries with water scarcity challenges (Omandi and Navalia 2020). Kenya and Tanzania, for example, use large-scale CWs to treat municipal and industrial wastewater. In Kenya, a hybrid wetland (horizontal subsurface and surface flow) is commonly used (Makopondo et al. 2020). However, more evidence on the development of wetland technologies in Africa is limited. Figures 3A-C shows the basic types of constructed wetland types.
Applying wetland hydrology, constructed wetlands are classified based on various parameters. Water flow regime (surface and subsurface) and macrophyte growth (emergent, submerged, free-floating, and floating-leaved plants) are the most important factors (Lamori et al. 2019). These factors are thought to be important in the biodegradation and biochemical transformation of various carbon sources and pernicious compounds (Sehar and Nasser 2019). The quality of the system's effluent is known to improve as the system's complexity and modifications increase (Vymazal and Kröpfelová 2008). Wetlands of various types are possible during wastewater treatment using CWs, including free water surface flow (FWSF) wetlands, subsurface flow (SSF) wetlands, and hybrid systems (HS). SSF is further classified into two types: horizontal flow SSF (HSSF) and vertical flow SSF (VSSF) (Biswal and Balasubramanian 2022). At the same time, the vegetation species used is an important parameter that further divides CWs into three major types: 1) emergent macrophyte CW, 2) submerged macrophyte CW, and 3) floating treatment wetland (FTW) systems, with rooted emergent macrophytes receiving the most attention (Stefanakis 2016). Table 7 provides some of the merits and draw backs of the various constructed wetlands designs. Table 8 summarises some of the removal efficiency observed with the use of different macrophytes in various constructed wetlands. It should be noted that temperature and climate conditions are important factors in plant development and growth (Raza et al. 2019).
11 Future perspectives
The current approach to enhancing the phytoremediation capabilities of macrophytes for the in-situ removal of industrial pollutants in a CW remains an ongoing endeavour. As the likelihood of floods and droughts increases in specific regions, climate change has emerged as a crucial factor to contemplate in designing CWs. Therefore, the efficacy of remediation programs will be influenced by the choice of plants, the function of CWs, and their incorporation into design methodologies. The integration of artificial intelligence and machine learning in conjunction with sensing technology that can simulate various conditions and potential adverse weather events is expected to optimize design parameters, enabling the system to respond appropriately (Singh et al. 2023).
At present, the process of bioremediating pollutants is predominantly conducted by microbial consortiums, which rely on the sequential production of enzymes by microorganisms to degrade complex compounds. The prediction of microbial population shifts over time by microbial succession indicates that the degradation community is in a constant state of flux. In contrast, the toxicity of polluted water is known to suppress the proliferation of microorganisms, often delaying the degradation process due to the necessary adaptation and acclimation periods. This has frequently been regarded as an inadequacy of the biological process, given the need for rapid toxic element removal. Nevertheless, the consistent advancements in functional omics, as well as our ability to identify plant and microbial species and genes involved in toxic element removal processes through expanding organism databases, will reduce the time lag for biological processes. This will enable the implementation of more targeted bioremediation programs. Phytoremediation processes will be enhanced by the accelerated access to references of novel enzymes on these data bases and the potential for synthesis. Furthermore, this will facilitate the identification of a greater variety of plant species with specialized phytodegradation functions, thereby enhancing our capacity to select and optimize pollution remediation processes (Wang et al. 2022).
The comprehension of plant responses to nanoparticles is a critical area of research as nanotechnology increasingly finds application in everyday life. It is imperative to recognize that they will evolve into the contaminants of the future. Hence, a comprehensive assessment of plant participation in nanoparticles removal from the environment and the underlying processes of migration, absorption, transformation, and accumulation capacities is crucial for proactive management of nanoparticles as waste. Thus, such insights will enhance our readiness to confront this possibility.
12 Conclusion
Macrophytes are considered an important component of the wetlands ecosystem not only as the habitat and energy source for aquatic life but, also for their capability to improve the quality of water by absorbing nutrients and inadvertently pollutants via their effective root systems and to function as powerful biofilters. The surge in industrial activities have resulted in the introduction of various organic and inorganic pollutants in aquatic systems, causing cascading effects on biodiversity and human health. Conventional remedial strategies have been implemented to eradicate these pollutants from the environment; however, with varying degrees of success. Phytoremediation has gained acceptance as an environmentally sustainable practice for removing pollutants from various wastewaters. Aquatic macrophytes when hosting endophytes benefit from their presence as they aid in plant growth as well as for the degradation of pernicious compounds via complex biochemical processes. Both endophytes and rhizospheric bacteria form these synergistic interspecific interactions that can be tailored to treat specific profile of industrial effluents. Such treatment regimens are best controlled in situ. Therefore, constructed wetlands can be readily applied. More recently, invasive macrophytes are being considered due to their numerous advantages obtained through evolution and adaptation. The prospect of such technology relies on optimising parameters such as finding out the best macrophyte-microbial assemblage to carry out pollutant degradation, broadening the investigation of hyperaccumulators for heavy metal remediation, as well as evolving strategies in retrofitting existing CWs with appropriate types of macrophytes. Moreover, in controlled in situ environments, it is possible to investigate and apply novel candidate genes for insertion into hosts to improved various enzyme expression and in this way increase degradation efficiency. Such application should take ethical issues into consideration and plan to ensure confinement of these alien species and novel genes and/or transformed plants and organisms to avoid their introduction to natural wetlands or other environments.
References
Abbas A, Ifran M, Khan S, Hassan A, Khan S, Javed R, Ali S (2021) Microbes: role in industries, medical field and impacts on health. Saudi J Med Pharm Sci 7(6):278–282. https://doi.org/10.36348/sjmps.2021.v07i06.010
Afzal M, Khan QM, Sessitsch A (2014) Endophytic bacteria: prospects and applications for the phytoremediation of organic pollutants. Chemosphere 117(1):232–242. https://doi.org/10.1016/j.chemosphere.2014.06.078
Aguirre-Garrido JF, Montiel-Lugo D, Hernández-Rodríguez C, Torres-Cortes G, Millán V, Toro N, Martínez-Abarca F, Ramírez-Saad HC (2012) Bacterial community structure in the rhizosphere of three cactus species from semi-arid highlands in central Mexico. Antonie Van Leeuwenhoek 101:891–904. https://doi.org/10.1007/s10482-012-9705-3
Ahsan MT, Najam-Ul-Haq M, Idrees M, Ullah I, Afzal M (2017) Bacterial endophytes enhance phytostabilization in soils contaminated with uranium and lead. Int J Phytoremediation 19(10):937–946. https://doi.org/10.1080/15226514.2017.1303813
Akram RT, Veysel H, Hafiz MA, Shakeel H, Sajjad H, Ahmad M, Muhammad M R, Muhammad IAR, Atta M, Nasir M, Faisal M, Muhammad S, Syeda RF, Shah A, Khizer S, Mazhar A, Yasir A, Haji MH, Sajjad W, Farhat M, Rabbia A, Asad Z, Syed ASulD, Muhammad NW (2018) Fate of Organic and Inorganic Pollutants in Paddy Soils. In: Hashmi, M., Varma, A. (eds) Environmental pollution of paddy soils. Soil biology. Springer, Cham, pp 53
Al-Tabatabai A-Z (2020) Aquatic plant (Hydrilla verticillata) roles in bioaccumulation of toxic elements. Iraqi J Agri Sci 51(2):574–584. https://doi.org/10.36103/ijas.v51i2.984
Alabid I, Glaesar SP, Kogel K-H (2018) Endofungal bacteria increase fitness of their host fungi and impact their association with crop plants. Curr Issues Mol Bio 30:59–74. https://doi.org/10.21775/cimb.030.059
Alam AKMR, Hoque S (2017) Phytoremediation of industrial wastewater by culturing aquatic macrophytes, Trapa natans L. and Salvinia cucullata Roxb. J Bio Sci 6:19–27. https://doi.org/10.22059/POLL.2017.234867.284
Alegria-Terrazas R, Giles C, Paterson E, Robertson-Albertyn S, Cesco S, Mimmo T, Pii Y, Bulgarelli D (2016) Plant-Microbiota Interactions as a driver of the mineral turnover in the Rhizosphere. Adv Appl Microbiol 95:1–67. https://doi.org/10.1016/bs.aambs.2016.03.001
Ali LA, Rowdha H, Hosam MS, Usama R, Muhammad AA, Salman S (2013) Soybean peroxidase-mediated degradation of an azo dye- A detailed mechanistic study. BMC Biochem 14(1):1–14. https://doi.org/10.1186/1471-2091-14-35
Allen LH (1997) Mechanisms and rates of O2 transfer to and through submerged rhizomes and roots via aerenchyma. Soil Crop Sci 56:41–54. https://pubag.nal.usda.gov/catalog/28385. Accessed 15 June 2023
Aly A, Debbab H, Proksch AP (2011) Fungal endophytes: unique plant inhabitants with great promises. Appl Microbiol Biotech 90(6):1829–1845. https://doi.org/10.1007/s00253-011-3270-y
Ambrose KV, Tian ZW, Yifei S, Jordan Z, Gerben H, Bingru B, Faith C (2015) Functional characterization of salicylate hydroxylase from the fungal endophyte Epichloë festucae. Sci Rep 5(1):1–12. https://doi.org/10.1038/srep10939
An J, Liu C, Wang Q, Rui J, Zhang S, Li X (2019) Soil bacterial community structure in Chinese wetlands. Geoderma 337(2):290–299. https://doi.org/10.1016/j.geoderma.2018.09.035
Aravind R, Eapen SJ, Kumar A, Dinu A, Ramana KV (2010) Screening of endophytic bacteria and evaluation of selected isolates for suppression of burrowing nematode (Radopholus similis Thorne) using three varieties of black pepper (Piper nigrum L.). Crop Prot 29(4):318–324. https://doi.org/10.1016/j.cropro.2009.12.005
Ashraf SA, Muhammad N, Muhammad S, Muhammad Z, Zahir A (2018) Endophytic bacteria enhance remediation of tannery effluent in constructed wetlands vegetated with Leptochloa fusca. Intl J Phytoremediation 20(2):121–128. https://doi.org/10.1080/15226514.2017.1337072
Azadi D, Shojaei H (2020) Biodegradation of polycyclic aromatic hydrocarbons, phenol and sodium sulfate by Nocardia species isolated and characterized from Iranian ecosystems. Sci Rep 10(1):1–12. https://doi.org/10.1038/s41598-020-78821-1
Babu AG, Kim JD, Oh BT (2013) Enhancement of heavy metal phytoremediation by Alnus firma with endophytic Bacillus thuringiensis GDB-1. J Hazard Mate 250(252):477–483. https://doi.org/10.1016/j.jhazmat.2013.02.014
Babu AG, Shea PJ, Sudhakar D, Jung IB, Oh BT (2015) Potential use of Pseudomonas koreensis AGB-1 in association with Miscanthus sinensis to remediate heavy metal(loid)-contaminated mining site soil. J Environ Manage 151:160–166. https://doi.org/10.1016/j.jenvman.2014.12.045
Bai L, Liu X-L, Hu J, Li J, Wang Z-L, Han G, Li S-L, Liu C-Q (2018) Heavy metal accumulation in common aquatic plants in rivers and lakes in the Taihu Basin. Intl J Environ Res Public Health 15(2857):1–12. https://doi.org/10.3390/ijerph15122857
Baker AJM, Mcgrath SP, Reeves RD, Smith JAC (2000) Metal hyperaccumulator plants: A review of the ecology and physiology of a biological resource for phytoremediation of metal-polluted soils. In: Terry N and Banuelos G (eds) Phytoremedediation of metal contaminated soil and water. Lewis, Boca Raton, Florida, U.S.A, pp 85–108
Bao S, Liang L, Huang J, Liu X, Tang W, Yi J, Fang T (2019) Removal and fate of silver nanoparticles in lab-scale vertical flow constructed wetland. Chemosphere 214:203–209. https://doi.org/10.1016/j.chemosphere.2018.09.110
Becerra-Castro C, Prieto-Fernández A, Álvarez-Lopez V, Monterroso C, Cabello-Conejo MI, Acea MJ, Kidd PS (2011) Nickel solubilizing capacity and characterization of rhizobacteria isolated from hyperaccumulating and non-hyperaccumulating subspecies of Alyssum Serpyllifolium. Intl J Phytoremediation 13(SUPPL.1):229–244. https://doi.org/10.1080/15226514.2011.568545
Bedford BL, Bouldin DR, Beliveau BD (1991) Net oxygen and carbon-dioxide balances in solutions bathing roots of wetland plants. J Ecol 1:943–959. https://doi.org/10.2307/2261090
Bingöl NA, Özmal F, Akın B (2017) Phytoremediation and Biosorption Potential of Lythrum salicaria L. for Nickel Removal from Aqueous Solutions. Poland J Environ Stud 26(6):2479–2485. https://doi.org/10.15244/pjoes/70628
Bisht S, Pandey P, Kaur G, Aggarwal H, Sood A, Sharma S, Kumar V, Bisht NS (2014) Utilization of endophytic strain Bacillus sp. SBER3 for biodegradation of polyaromatic hydrocarbons (PAH) in soil model system. Eur J Soil Biol 60:67–76. https://doi.org/10.1016/j.ejsobi.2013.10.009
Bisht S, Pandey P, Bhargava B, Sharma S, Kumar V, Sharma KD (2015) Bioremediation of polyaromatic hydrocarbons (PAHs) using rhizosphere technology. Brazilian J Microbiol 46(1):7–21. https://doi.org/10.1590/s1517-838246120131354
Biswal BK, Balasubramanian R (2022) Constructed wetlands for reclamation and reuse of wastewater and urban stormwater: a review. Frontiers Environ Sci 10(836289):1–21. https://doi.org/10.3389/fenvs.2022.836289
Blaylock MJ, Elles MP, Huang JW, Dushenkov V (1999) Phytoremediation of lead-contaminated soil at a New Jersey Bronwfield site. Remediation J 9(3):93–101. https://doi.org/10.1002/rem.3440090308
Borgulat J, Ponikiewska K, Jałowiecki Ł, Strugała-Wilczek A, Płaza G (2022) Are wetlands as an integrated bioremediation system applicable for the treatment of wastewater from underground coal gasification processes? Energies 15:1–19. https://doi.org/10.3390/en15124419
Branković S, Glišić R, Topuzović M, Marin M (2015) Uptake of seven metals by two macrophytes species: potential for phytoaccumulation and phytoremediation. Chemi Ecol 31(7):583–593. https://doi.org/10.1080/02757540.2015.1077812
Chen Y, Xie XG, Ren CG, Dai CC (2013) Degradation of N-heterocyclic indole by a novel endophytic fungus Phomopsis liquidambari. Bioresour Technol 129:568–574. https://doi.org/10.1016/j.biortech.2012.11.100
Chen F, Ren CG, Zhou T, Wei Y-J, Dai C-C (2016) A novel exopolysaccharide elicitor from endophytic fungus Gilmaniella sp. AL12 on volatile oils accumulation in Atractylodes lancea. Sci Rep 6(1):1–17. https://doi.org/10.1038/srep34735
Chen C, Wang W, Wang J (2019a) Phytoremediation of cadmium-contaminated soil by Sorghum bicolor and the variation of microbial community. Chemosphere 235:985–994. https://doi.org/10.1016/J.CHEMOSPHERE.2019.07.028
Chen M, He S, Li J, Hu W, Ma Y, Wu L, Gang G (2019b) Co-occurrence patterns between bacterial and fungal communities in response to a vegetation gradient in a freshwater wetland. Can J Microbiol 5(10):722–737. https://doi.org/10.1139/cjm-2019-0147
Cheung MK, Wong CK, Chu KH, Kwan HS (2018) Community structure, dynamics and interactions of bacteria, archae and fungi in subtropical coastal wetland sediments. Sci Rep 8(14397):1–14. https://doi.org/10.1038/s41598-018-32529-5
Chowdhury NS, Farjana F, Sohrab MdH (2020) Isolation, identification and pharmacological activities of endophytic fungi from Aponogeton undulatus roxb. Pharmacol Phar 11:350–361. https://doi.org/10.4236/pp.2020.1112028
Clairmont LK, Stevens KJ, Slawson RM (2019) Site-specific differences in microbial community structure and function within the rhizosphere and rhizoplane of wetland plants is plant species dependent. Rhizosphere 9:56–68. https://doi.org/10.1016/j.rhisph.2018.11.006
Clemens S, Kim EJ, Neumann D, Schroeder JI (1999) Tolerance to toxic metals by a gene family of phytochelatin synthases from plants and yeast. EMBO J 18(12):3325–3333. https://doi.org/10.1093/2Femboj/2F18.12.3325
Clemens SP, Krämer MG, Ute. (2002) A long way ahead: understanding and engineering plant metal accumulation. Trends Plant Sci 7(7):309–315. https://doi.org/10.1093/emboj/18.12.3325
Collins B, McArthur JV, Sharitz RR (2004) Plant effects on microbial assemblages and remediation of acidic coal pile runoff in mesocosm treatment wetlands. Ecol Eng 23:107–115. https://doi.org/10.1016/j.ecoleng.2004.07.005
Correa-Garcia S, Pande PV, Seguin A, St-Arnaud M, Yergeau E (2018) Rhizoremediation of petroleum hydrocarbons: a model system for plant microbe manipulation. Microb Biotechnol 11(5):1–14. https://doi.org/10.1111/2F1751-7915.13303/
DalCorso G, Fasani E, Manara A, Visioli G (2019) Furini A (2019) Heavy Metal Pollutions: State of the Art and Innovation in Phytoremediation. Intl J Mol Sci 20(14):3412. https://doi.org/10.3390/2Fijms20143412
Dalecka B, Strods M, Cacivkins P, Ziverte E, Rajarao GK, Juhna T (2021) Removal of pharmaceutical compounds from municipal wastewater by bioaugmentation with fungi: An emerging strategy using fluidized bed pelleted bioreactor. Environ Adv 5:100086. https://doi.org/10.1016/j.envadv.2021.100086
Daley DJ, Kucera LN (2014) Potential role of constructed wetlands for treatment of pharmaceuticals and personal care products in wastewater. Clear Waters 31:1–4. https://doi.org/10.1016/j.watres.2020.116448
Da Silva PV, Maciel L d-S, Castro LS, Murat PG, Junior MGH, Zerlotti PH, Motta-Castro ARC, Pontes ERJC (2018) Enteroparasites in riverside settlements in the Pantanal wetlands ecosystem. J Parasitol Res 6839745:1-5https://doi.org/10.1155/2018/6839745
Das N, Bhattacharya S, Maiti MK (2016) Enhanced cadmium accumulation and tolerance in transgenic tobacco overexpressing rice metal tolerance protein gene OsMTP1 is promising for phytoremediation. Plant Physiol Biochem 105:297–309. https://doi.org/10.1016/j.plaphy.2016.04.049
De Mandal S, Laskar F, Panda AK, Mishra R (2020) Microbial diversity and functional potential in wetland ecosystems. Recent Advancements in Microbial Diversity. Academic Press, pp 289–314
Deikman J (1997) Molecular mechanisms of ethylene regulation of gene transcription. Physiol Plant 3:561–566. https://doi.org/10.1111/j.1399-3054.1997.tb03061.x
Dell’Amico E, Cavalca L, Andreoni V (2005) Analysis of rhizobacterial communities in perennial Graminaceae from polluted water meadow soil, and screening of metal-resistant, potentially plant growth-promoting bacteria. FEMS Microbiol Ecol 52(2):153–162. https://doi.org/10.1016/j.femsec.2004.11.005
De Oliveira M, Atalla AA, Frihling BEF, Cavalherl PS, Migliolo L, Filho FJCM (2019) Ibuprofen and caffeine removal in vertical flow and free-floating macrophyte constructed wetlands with heliconia rostrata and eichornia crassipes. Chem Eng J 373:458–467. https://doi.org/10.1016/j.cej.2019.05.064
Deng Z, Cao L (2017) Fungal endophytes and their interactions with plants in phytoremediation: a review. Chemosphere 168:1100–1106. https://doi.org/10.1016/j.chemosphere.2016.10.097
Deutsch Y, Gur L, Berman FI, Ezra D (2021) Endophytes from algae, a potential source for new biologically active metabolites for disease management in aquaculture. Front Mar Sci 8(636636):1–13. https://doi.org/10.3389/fmars.2021.636636
Doty SL, Freeman JL, Cohu CM, Burken JG, Firrincieli A, Simon A, Khan Z, Isebrands JG, Lukas J, Blaylock MJ (2017) Enhanced degradation of TCE on a superfund site using endophyte-assisted poplar tree phytoremediation. Environ Sci Technol 51(17):10050–10058. https://doi.org/10.1021/acs.est.7b01504
Dong H, Onstott TC, Deflaun MF, Fuller ME, Scheibe TD, Streger SH, Rothmel RK, Mailloux BJ (2002) Relative dominance of physical versus chemical effects on the transport of adhesion-deficient bacteria in intact cores from South Oyster, Virginia. Environ Sci Technol 36(5):891–900. https://doi.org/10.1021/es010144t
Du S, Dini-Andreote F, Zhang N, Liang C, Yao Z, Zhang H, Zhang D (2020) Divergent co-occurrence patterns and assembly processes structure the abundnat and reare batcerial communities in a salt marsh ecosystem. Appl Environ Microbiol 86(13). https://doi.org/10.1128/AEM.00322-20
Eskandary S, Tahmourespour A, Hoodaji M, Abdollahi A (2017) The synergistic use of plant and isolated bacteria to clean up polycyclic aromatic hydrocarbons from contaminated soil. J Environ Health Sci 15(12):1–8. https://doi.org/10.1186/s40201-017-0274-2
Engida T, Alemu T, Wu J, Xu D, Zhou Q, Wu Z (2020) Analysis of constructed wetlands technology performance efficiency for the treatment of floriculture industry wastewater, in Ethiopia. J Water Process Eng 38(101586):1–9. https://doi.org/10.1016/j.jwpe.2020.101586
Etesami H (2018) Bacterial mediated alleviation of heavy metal stress and decreased accumulation of metals in plant tissues: Mechanisms and future prospects. Ecotox Environ Saf 147:175–191. https://doi.org/10.1016/j.ecoenv.2017.08.032
Fang J, Dong J, Li C, Chen H, Wang L, Lyu T, He H, Liu J (2021) Response of microbial composition and function to emergent plant rhizosphere of a constructed wetland in northern China. Appl Soil Ecol 168:104–141. https://doi.org/10.1016/j.apsoil.2021.104141
Ferrarini A, Fracasso A, Spini G, Fornasier F, Taskin E, Fontanella MC, Beone GM, Amaducci S, Puglisi E (2021) Bioaugmented phytoremediation of metal-contaminated soils and sediments by hemp and giant reed. Front Microbiol 12(645893):1–20. https://doi.org/10.3389/fmicb.2021.645893
Fasani E, Manara A, Martini F, Furini A, DalCorso G (2018) The potential of genetic engineering of plants for the remediation of soils contaminated with toxic elements. Plant, Cell Environ 41(5):1201–1232. https://doi.org/10.1111/pce.12963
Freed G, Schlatter D, Paulitz T, Dugan F (2019) Mycological insights into wetland fungal communities: The mycobiome of Camassia in the Pacific Northwest. Phytobiomes J 3:286–299. https://doi.org/10.1094/PBIOMES-04-19-0022-R
Fu W, Xu M, Sun K, Hu L, Cao W, Dai C, Jia Y (2018) Biodegradation of phenanthrene by endophytic fungus Phomopsis liquidambari in vitro and in vivo. Chemosphere 203:160–169. https://doi.org/10.1016/j.chemosphere.2018.03.164
Fu L, Xie R, Ma D, Zhang M, Liu L (2023) Variations in soil microbial community structure and extracellular enzymatic activities along a forest-wetland ecotone in high-latitude permafrost regions. Ecol Evol 13(6):160–169. https://doi.org/10.1002/ece3.10205
Gadd GM (2010) Metals, minerals and microbes: Geomicrobiology and bioremediation. Microbiol Reading 6(3):609–643
Garnica-Vergara A, Barrera-Ortiz S, Muñoz-Parra E, Raya-González J, Méndez-Bravo A, Macías-Rodríguez L, Ruiz-Herrera LF, López-Bucio J (2016) The volatile 6-pentyl-2h-pyran-2-one from Trichoderma atroviride regulates Arabidopsis thaliana root morphogenesis via auxin signaling and ethylene insensitive 2 functioning. New Phytol 209:1496–1512. https://doi.org/10.1111/nph.13725
Germaine KJ, Liu X, Cabellos GG, Hogan JP, Ryan D, Dowling DN (2006) Bacterial endophyte-enhanced phytoremediation of the organochlorine herbicide 2,4-dichlorophenoxyacetic acid. FEMS Microbiol Ecol 57(2):302–310. https://doi.org/10.1111/j.1574-6941.2006.00121.x
Ghermandi A, Van Den Bergh JC, Brander LM, de Groot HL, Nunes PA (2010) Values of natural and human-made wetlands: a meta-analysis. Water Resour Res 46(12):1–12. https://doi.org/10.1029/2010WR009071
Gill LW, Ring P, Casey B, Higgins NMP, Johnston PM (2017) Long term heavy metal removal by a constructed wetland treating rainfall runoff from a motorway. Sci Total Environ 601–602:32–44. https://doi.org/10.1016/j.scitotenv.2017.05.182
Glick BR (2014) Bacteria with ACC deaminase can promote plant growth and help to feed the world. Microbiol Res 169(1):30–39. https://doi.org/10.1016/j.micres.2013.09.009
Göhre V, Paszkowski U (2006) ‘Contribution of the arbuscular mycorrhizal symbiosis to heavy metal phytoremediation. Planta 223(6):1115–1122. https://doi.org/10.1007/s00425-006-0225-0
Gorgoglione A, Torretta V (2018) Sustainable management and successful application of constructed wetlands: a critical review. Sustainability 10(11):3910. https://doi.org/10.3390/su10113910
Govarthanan M, Mythili R, Selvankumar T, Kamala-Kannan S, Rajasekar A, Chang Y-C (2016) Bioremediation of toxic elements using an endophytic bacterium Paenibacillus sp. RM isolated from the roots of Tridax procumbens. 3 Biotech 6:242. https://doi.org/10.1007/s13205-016-0560-1
Grishchenkov VG, Shishmakov DA, Kosheleva IA, Boronin AM (2003) Growth of bacteria degrading naphthalene and salicylate at low temperatures. Prikl Biokhim Mikrobiol 39(3):322–328
Guittonny-Philippe A, Petit M-E, Masotti V, Monnier Y, Malleret L, Coulomb B, Combroux I, Baumberger T, Viglione J, Laffont-Schwob I (2015) Selection of wild macrophytes for use in constructed wetlands for phytoremediation of contaminant mixtures. J Environ Manage 147:108. https://doi.org/10.1016/j.jenvman.2014.09.009
Gupta S, Chaturvedi P, Kulkarni MG, Van Staden J (2020) A critical review on exploiting the pharmaceutical potential of plant endophytic fungi. Biotechnol Adv 39(107462). https://doi.org/10.1016/j.biotechadv.2019.107462
Hall JL (2002) Cellular mechanisms for heavy metal detoxification and tolerance. J Exp Bot 53(366):1–11. https://doi.org/10.1093/JEXBOT/53.366.1
Hamelink J, Landrum PF, Bergman H, Benson WH (1994) Bioavailability: physical, chemical, and biological interactions. In: Hamelink J, Landrum PF, Bergman H, Benson WH (eds) Handbook of Laboratory Science, 1st edn. CRC Press
van Hardoim PR, Overbeek LS, van Elsas JD (2008) Properties of bacterial endophytes and their proposed role in plant growth. Trends Microbiol 16(10):463–471. https://doi.org/10.1016/j.tim.2008.07.008
Hassani MA, Durán P, Hacquard S (2018) Microbial interactions within the plant holobiont. Microbiome 6(1):58. https://doi.org/10.1186/s40168-018-0445-0
Hassan I, Chowdhury SR, Prihartato PK, Razzak SA (2021) Wastewater treatment using constructed wetland: current trends and future potential. Processes 9:1–27. https://doi.org/10.3390/pr9111917
Hassanzadeh M, Zarkami R, Sadeghi R (2021) Uptake and accumulation of toxic elements by water body and Azolla filiculoides in the Anzali wetland. Appl Water Sci 11(91):1–8. https://doi.org/10.1007/s13201-021-01428-y
He H, Ye Z, Yang D, Yan J, Xiao L, Zhong T, Yuan M, Cai X, Fang Z, Jing Y (2013) Characterization of endophytic Rahnella sp. JN6 from Polygonum pubescens and its potential in promoting growth and Cd, Pb, Zn uptake by Brassica napus. Chemosphere 90(6):1960–1965. https://doi.org/10.1016/j.chemosphere.2012.10.057
Henderson L, Wilson JRU (2017) Changes in the composition and distribution of alien plants in South Africa: an update from the Southern African Plant Invaders Atlas. Bothalia- Afr Biodiv Conser 47(2):1–26. https://doi.org/10.4102/abc.v47i2.2172
Hill MP, Coetzee JA, Martin GD, Smith R, Strange EF (2020) Invasive alien aquatic plants in South African freshwater ecosystems. Biological invasions in South Africa. Springer International Publishing, pp 97–114. https://doi.org/10.1007/978-3-030-32394-3_4
Hill MP, Coetzee J (2017) The biological control of aquatic weeds in South Africa: current status and future challenges. Bothalia 47(2):1–12. https://doi.org/10.4102/abc.v47i2.2152
Hong Y, Liao D, Hu A, Wang H, Chen J, Khan S, Su J, Li H (2015) Diversity of endophytic and rhizoplane bacterial communities associated with exotic Spartina alterniflora and native mangrove using Illumina amplicon sequencing. Canadian J Microbiol 61(10):23–733. https://doi.org/10.1139/cjm-2015-0079
Hou C, Shi X, Liu G, Liu S, Zhu X, Xu H (2016) Use of protozoa for assessing water quality in a humid subptropical urban wetland ecosystem, Southern China. Environ Pollut Climate Change 1(103):1–7. https://doi.org/10.4172/2573-458X.1000105
Huang J, Liu Z, Li S, Xu B, Gong Y, Yang Y, Sun H (2016) Isolation and engineering of plant growth promoting rhizobacteria Pseudomonas aeruginosa for enhanced cadmium bioremediation. J Gen Appl Microbiol 62:258–265. https://doi.org/10.2323/jgam.2016.04.007
Huang R, Zeng J, Zhao D, Cook KV, Hambright DK, Zhongbo Y (2020) Sediment microbiomes associated with the rhizosphere of emergent macrophytes in a shallow, subtropical lake. Limnol Oceanogr 65:S38–S48. https://doi.org/10.1002/lno.11325
Hwang JI, Li Z, Andreacchio N, Ordonez-hinz F, Wilson PC (2020) Potential use of floating treatment wetlands established with Canna flaccida for removing organic contaminants from surface water. Intl J Phytoremediation 22(12):1304–1312. https://doi.org/10.1080/15226514.2020.1768511
Iha D, Bianchini J (2015) Phytoremediation of Cd, Ni, Pb, Zn by Salvinia minima. Intl J Phytoremediation 17(10):929–935. https://doi.org/10.1080/15226514.2014.1003793
Illescas M, Rubio MB, Hernandez-Ruiz V, Moran-Diez ME, de Alba AEM, Nicolas C, Monte E, Hermosa R (2020) Effect of inorganic N top dressing and Trichoderma harzianum seed-inoculation on crop yield and the shaping of root microbial communities of wheat plants cultivated under high basal N fertilization. Front Plant Sci 11(675861):1–21. https://doi.org/10.3389/fpls.2020.575861
Ijaz A, Iqbal Z, Afzal M (2016) Remediation of sewage and industrial effluent using bacterially assisted floating treatment wetlands vegetated with Typha domingensis. Water Sci Technol 9:2192–2201. https://doi.org/10.2166/wst.2016.405
Iqbal A, Arshad M, Hashmi I, Karthikeyan R, Gentry TJ, Schwab AP (2018) Biodegradation of phenol and benzene by endophytic bacterial strains isolated from refinery wastewater-fed Cannabis sativa. Environ Technol 39(13):1705–1714. https://doi.org/10.1080/09593330.2017.1337232
Jahangir MMR, Richards KG, Healy MG, Gill L, Müller C, Johnston P, Fenton O (2016) Carbon and nitrogen dynamics and greenhouse gas emissions in constructed wetlands treating wastewater: a review. Hydrol Earth Syst Sci 20:109–123. https://doi.org/10.5194/hess-20-109-2016
Jamion NA, Ismail FIS, Wahid NSA, Nassim NSA (2021) A preliminary study of potential aquatic macrophytes in phytoremediation of lead in The Muar River. Malaysian J Chem 23(2):152–164. https://ikm.org.my/publications/malaysian-journal-of-chemistry/view-abstract.php?abs=J0031-A00296. Accessed 14 June 2023
Jing Z, Deng S, Wen Y, Jin Y, Pan L, Zhang Y, Black T, Jones KC, Zhang H, Zhang D (2019) Application of Simplicillium chinense for Cd and P biosoprtion and enhancing heavy metal phytoremdiation of soils. Sci Total Environ 697:134–148. https://doi.org/10.1016/j.scitotenv.2019.134148
Joergensen RG, Wichern F (2018) Alive and kicking: why dormant soil microorganisms matter. Soil Biol Biochem 116:419–430. https://doi.org/10.1016/j.soilbio.2017.10.022
Juwarkar AA, Nair A, Dubey KV, Singh SK, Devotta S (2007) Biosurfactant technology for remediation of cadmium and lead contaminated soils. Chemosphere 68(10):1996–2002. https://doi.org/10.1016/j.chemosphere.2007.02.027
Kanaly RA, Harayama S (2010) Advances in the field of high-molecular-weight polycyclic aromatic hydrocarbon biodegradation by bacteria. Microb Biotechnology 3(2):136–164. https://doi.org/10.1111/j.1751-7915.2009.00130.x
Kang SH, Singh S, Kim J-Y, Lee W, Mulchandani A, Chen W (2007) Bacteria metabolically engineered for enhanced phytochelatin production and cadmium accumulation. Appl Environ Microbiol 73(19):6317–6320. https://doi.org/10.1128/aem.01237-07
Kang JW, Khan Z, Doty SL (2012) Biodegradation of trichloroethylene by an endophyte of hybrid poplar. Appl Environ Microbiol 78(9):3504–3507. https://doi.org/10.1128/2FAEM.06852-11
Karaś MA, Wdowiak-Wróbel S, Sokołowski W (2021) Selection of endophytic strains for enhanced bacteria-assisted phytoremediation of organic pollutants posing a public health hazard. Intl J Mol Sci 22(17):9557. https://doi.org/10.3390/ijms22179557
Kaul S, Gupta S, Ahmed M, Dhar MK (2012) Endophytic fungi from medicinal plants: a treasure hunt for bioactive metabolites. Phytochem Rev 11:487–505. https://doi.org/10.1007/s11101-012-9260-6
Kaushal M, Patil MD, Wani SP (2018) Potency of constructed wetlands for deportation of pathogens index from rural, urban and industrial wastewater. Intl J Environ Sci Technol 15(3):637–648. https://doi.org/10.1007/s13762-017-1423-y
Kassin NFA, Habibuddin AM, Juliana JL (2015) Heavy metal removal using Cabomba Caroliniana as submerged vegetation species in constructed wetland. In: Hassan R, Yusoff M, Alisibramulisi A, Mohd Amin N, Ismail Z (eds) InCIEC 2014. Springer, Singapore
Khan Z, Roman D, Kintz T, delas Alas M, Yap R, Doty S (2014) Degradation, phytoprotection and phytoremediation of phenanthrene by endophyte Pseudomonas putida, PD1. Environ Sci Technol 48(20):12221–12228. https://doi.org/10.1021/es503880t
Khan N, Khan J, Ullah R, Ali K, Jones DA, Khan MEH (2022) Toxic elements Contaminants in Watercress (Nasturtium officinale R. BR.): Toxicity and Risk Assessment for Humans along the Swat River Basin, Khyber Pakhtunkhwa, Pakistan. Sustainability 14(4690):1–15. https://doi.org/10.3390/su14084690
Kochi LY, Freitas PL, Maranho LT, Juneau P, Gomes MP (2020) Aquatic macrophytes in constructed wetlands: a fight against water pollution. Sustainability (Switzerland) 12:1–21. https://doi.org/10.3390/su12219202
Kos G, Ryzhkov A, Dastoor A, Narayan J, Steffen A, Ariya PA, Zhang L (2012) Evaluation of discrepancy between measured and modelled oxidised mercury species. Atmos Chem Phys 12:17245–17293. https://doi.org/10.5194/acp-13-4839-2013
Kosolapov DB, Kuschk P, Vainshtein MB, Vatsourina AV, Wiessner A, Kästner M, Müller RA (2004) Microbial processes of heavy metal removal from carbon-deficient effluents in constructed wetlands. Engin Life Sci 5:403–411. https://doi.org/10.1002/elsc.200420048
Kozminska A, Wiszniewska A, Hanus-Fajerska E, Muszynska E (2018) Recent strategies of increasing metal tolerance and phytoremediation potential using genetic transformation of plants. Plant Biotechnol Rep 12:1–14. https://doi.org/10.1007/s11816-017-0467-2
Krzmarzick MJ, Taylor DK, Fu X, McCutchan AL (2018) Diversity and niche of archaea in bioremediation. Archaea 2018. https://doi.org/10.1155/2018/3194108
Kumar V, AlMomin S, Al-Shatti A, Al-Aqeel H, Al-Salameen F, Shajan AB, Nair SM (2019) Enhancement of heavy metal tolerance and accumulation efficiency by expressing Arabidopsis ATP sulfurylase gene in alfalfa. Intl J Phytoremediation 21:1112–1121. https://doi.org/10.1080/15226514.2019.1606784
Kumar A, Tripti VO, Maleva M, Panikovskaya K, Borisova G, Rajkumar M, Bruno LB (2021) Bioaugmentation with copper tolerant endophyte Pseudomonas lurida strain EOO26 for improved plant growth and copper phytoremediation by Helianthus annuus. Chemosphere 266:128983. https://doi.org/10.1016/j.chemosphere.2020.128983
Kumari K, Naskar M, Aftabuddin M, Sakar SD, Ghosh BD, Aarkar UK, Nag SK, Jana C, Das BK (2021) Evaluation of three prokaryote primers for identification of prokaryote community structure and their adobe preference in three distinct wetland ecosystems. Front Microbiol 12(643945):1–21. https://doi.org/10.3389/fmicb.2021.643945
Kurniawan SB, Ramli NN, Said NSM, Alias J, Imron MF, Abdullah SRS, Othman AR, Purwanti IF, Hasan HA (2022) Practical limitations of bioaugmentation in treating heavy metal contaminated soil and role of plant growth promoting bacteria in phytoremediation as a promising alternative approach. Heliyon 8(4). https://doi.org/10.1016/j.heliyon.2022.e08995
Kyambadde J, Kanslime F, Gumaelius L, Dalhammar G (2004) A comparative study of Cyperus papyrus and Miscanthidium violaceum-based constructed wetlands for wastewater treatment in a tropical climate. Water Res 38(2):475–485. https://doi.org/10.1016/j.watres.2003.10.008
Lasat MM (1999) Phytoextraction of metals from contaminated soil: a review of plant/soil/metal interaction and assessment of pertinent agronomic issues. J Hazard Subst Res 2(1):5. https://doi.org/10.4148/1090-7025.1015
Lemaire B, Van Oevelen S, De Block P, Verstraete B, Smets E, Prinsen E, Dessein S (2012) Identification of the bacterial endosymbionts in leaf nodules of Pavetta (Rubiaceae). Intl J Syst Evol Microbiol 62(Pt 1):202–209. https://doi.org/10.1099/ijs.0.028019-0
Lamers LP, van Diggelen JM, Op den Camp HJ, Visser EJ, Lucassen EC, Vile MA, Jetten MS, Smolders AJ, Roelofs JG (2012) Microbial transformations of nitrogen, sulfur, and iron dictate vegetation composition in wetlands: a review. Front Microbiol 3:156. https://doi.org/10.3389/fmicb.2012.00156
Lamori JG, Xue J, RachmadI AT, Lopes GU, Kitajima M, Gerba CP, Pepper IL, Brooks JP, Sherchan S (2019) Removal of faecal indicator bacteria and antibiotic resistant genes in constructed wetlands. Environ Sci Pollut Res 26(10):10188–10197. https://doi.org/10.1007/s11356-019-04468-9
Leroy C, Jauneau A, Martinez Y, Cabin-Flaman A, Gibouin D, Orivel J, Séjalon-Delmas N (2017) Exploring fungus–plant N transfer in a tripartite ant–plant–fungus mutualism. Ann Bot 120(3):417–426. https://doi.org/10.1093/aob/mcx064
Lumactud R, Shen SY, Lau M, Fulthorpe R (2016) Bacterial endophytes isolated from plants in natural oil seep soils with chronic hydrocarbon contamination. Front Microbiol 7(775). https://doi.org/10.3389/fmicb.2016.00755.
Ma Y, Prasad MNV, Rajkumar M, Freitas H (2011) Plant growth promoting rhizobacteria and endophytes accelerate phytoremediation of metalliferous soils. Biotechnol Adv 29(2):248–258. https://doi.org/10.1016/j.biotechadv.2010.12.001
Ma Y, Oliveira RS, Nai F, Rajkumar M, Luo Y, Rocha I, Freitas H (2015) The hyperaccumulator Sedum plumbizincicola harbors metal-resistant endophytic bacteria that improve its phytoextraction capacity in multi-metal contaminated soil. J Environ Manage 156:62–69. https://doi.org/10.1016/j.jenvman.2015.03.024
Ma Y, Rajkumar M, Zhang C, Freitas H (2016) Beneficial role of bacterial endophytes in heavy metal phytoremediation. J Environ Manage 174:14–25. https://doi.org/10.1016/J.JENVMAN.2016.02.047
Madera-Parra CA, Ríos DA (2017) Constructed wetlands for landfill leachate treatment. In: Rene E, Sahinkaya E, Lewis A, Lens P (eds.) Sustainable Heavy Metal Remediation: Principles and Processes. 1. pp 121–63
Makopondo ROB, Rotich LK, Kamau CG (2020) Potential use and challenges of constructed wetlands for wastewater treatment and conservation in game lodges and resorts in Kenya. Sci World J 9184192:1–9. https://doi.org/10.1155/2020/9184192
Mahabali S, Spanoghe P (2014) Mitigation of two insecticides by wetland plants: feasibility study for the treatment of agricultural runoff in Suriname (South America). Water Air Soil Pollut 225:1771. https://doi.org/10.1007/s11270-013-1771-2
Mahboobe G-Z, Saeid E, Kaveh O-A-A, Vijay PS (2017) Irrigation with waste water treated by constructed wetlands. IJRSAS 3(11):18–34. https://doi.org/10.20431/2454-6224.0311002
Mahesh VB, Jayasankar R, Madhavan A (2020) Bioremediation of industrial effluent at source using aquatic macrophytes. J Mar Biol Ass India 62(2):63–71. https://doi.org/10.6024/jmbai.2020.62.2.2187-07
Mangangka IR (2013) Role of hydraulic factors in constructed wetland and bioretention basin treatment performance. Doctoral dissertation, Queensland University of Technology, Queensland
Marques APGC, Rangel AOSS, Castro PML (2011) Remediation of heavy metal contaminated soils: an overview of site remediation techniques. Crit Rev Environ Sci Technol 41(10):879–914. https://doi.org/10.1080/10643380903299517
Matamoros V, Rodríguez Y, Bayona JM (2017) Mitigation of emerging contaminants by full-scale horizontal flow constructed wetlands fed with secondary treated wastewater. Ecol Eng 99:222–227. https://doi.org/10.1016/j.ecoleng.2016.11.054
Mendes R, Garbeva P, Raaijmakers JM (2013) The rhizosphere microbiome: significance of plant beneficial, plant pathogenic, and human pathogenic microorganisms. FEMS Microbiol Rev 37:634–663. https://doi.org/10.1111/1574-6976.12028
Mgobozi V (2014) Heavy Metal Content Absorption and Medicinal Potential of Egeria Densa (Planch.) Casp. Doctoral dissertation, University of Fort Hare
Mitter B, Petric A, Shin MW, Chain PS, Hauberg-Lotte L, Reinhold-Hurek B, Nowak J, Sessitsch A (2013) Comparative genome analysis of Burkholderia phytofirmans PsJN reveals a wide spectrum of endophytic lifestyles based on interaction strategies with host plants. Front Plant Sci 4:120. https://doi.org/10.3389/fpls.2013.00120
Muehe EM, Weigold P, Adaktylou IJ, Planer-Friedrich B, Kraemer U, Kappler A, Behrens S (2015) Rhizosphere microbial community composition affects cadmium and zinc uptake by the metal-hyperaccumulating plant Arabidopsis halleri. Appl Environ Microbiol 81(6):2173–2181. https://doi.org/10.1128/aem.03359-14
Muhamad MH, Abdullah SRS, Hasan HA, Bakar SNHA, Kurniawan SB, Ismail NI (2021) A hybrid treatment system for water contaminated with pentachlorophenol: removal performance and bacterial community composition. J. Water Proc Eng 43. https://doi.org/10.1016/j.jwpe.2021.102243
Nanseu-Njiki CP, Dedzo GK, Ngameni E (2010) Study of the removal of paraquat from aqueous solution by biosorption onto Ayous (Triplochiton schleroxylon) sawdust. J Hazard Mater 179(1–3):63–71. https://doi.org/10.1016/j.jhazmat.2010.02.058
Nazir MI, Idrees I, Danish P, Ahmad S, Ali Q, Malik A (2020) Potential of water hyacinth (Eichorna crasspes L.) for phytoremediation of toxic elements from waste water. Bio Clin Sci Res J (1). https://doi.org/10.54112/bcsrij.v2020i1.6
Neori A, Agami M (2017) The functioning of rhizosphere biota in wetlands- a review. Wetlands 37:615–633. https://doi.org/10.1007/s13157-016-0757-4
Ndlovu MS (2020) Managing the invasive aquatic plant Sagittaria platyphylla (Engelm.) J.G. Sm (Alismataceae): problems and prospects. MSc Dissertation, Rhodes University, Makhanda
Nicholls AM, Tarun K (2003) Effects of lead and copper exposure of invasive weed, Lythrum salicaria L. (purple loosestrife). Ohio J Sci 103(5):129. http://hdl.handle.net/1811/23985. Accessed 14 June 2023
Nivala J, Kahl S, Boog J, Van Afferden M, Reemtsma T, Müller RA (2019) Dynamics of emerging organic contaminant removal in conventional and intensified subsurface flow treatment wetlands. Sci Total Environ 649:1144–1156. https://doi.org/10.1016/j.scitotenv.2018.08.339
Novita VZ, Moersidik SS, Priadi CR (2019) Phytoremediation potential of Pistia stratiotes to reduce high concentration of Copper (Cu) in acid mine drainage. IOP Conf Ser: Earth Environ Sci 355(012063):1–8. https://doi.org/10.1088/1755-1315/355/1/012063
Nwankwegu AS, Zhang L, Xie D, Onwosi CO, Muhammad WI, Odoh CK, Sam K, Idenyi JN (2022) Bioaugmentation as a green technology for hydrocarbon pollution remediation. Problems and prospects. J Environ Manage 304:114313. https://doi.org/10.1016/j.jenvman.2021.114313
Nxumalo MM, Lalla R, Renteria JL, Martin G (2016) Hydrocleys nymphoides (Humb. and Bonpl. ex Willd.) Buchenau: first record of naturalisation in South Africa. BioInvasions Rec 5(1):1–6. https://doi.org/10.3391/bir.2016.5.1.01
Olanrewaju OS, Ayangbenro AS, Glick BR, Babalola OO (2019) Plant health: feedback effect of root exudates-rhizobiome interactions. Appl Microbiol Biotechnol 103:1155–1166. https://doi.org/10.1016/j.chemosphere.2006.03.007
Omandi DO, Navalia AC (2020) Constructed wetlands in wastewater treatment and challenges of emerging resistant genes filtration and reloading. In: Devlin A, Pan J, Shah MM (eds). Inland Waters - Dynamics and Ecology. IntechOpen
Onaebi CN, Okoro AC, Ayaogu E (2020) Fungal diversity in the rhizosphere and rhizoplane of Okra (Abelmoschus esculentus L.) Moench. in Nsukka, Enugu State, Nigeria. Ann Res Rev Bio 35(3):14–22. https://doi.org/10.9734/arrb/2020/v35i330196.
Osa JRF, Apuan DA (2018) Water spinach (Ipomoea aquatica) as potential macrophytes to remediate acid mine drainage (AMD). Intl J Biosci 13(5):161–167. https://doi.org/10.1016/j.aquaeng.2014.04.002
Padmavathiamma PK, Li LY (2012) Rhizosphere influence and seasonal impact on phytostabilisation of metals—a field study. Water Air Soil Pollut 223:107–124. https://doi.org/10.1007/s11270-011-0843-4
Pawlik M, Cania B, Thijs S, Vangronsveld J, Piotrowska-Seget Z (2017) Hydrocarbon degradation potential and plant growth-promoting activity of culturable endophytic bacteria of Lotus corniculatus and Oenothera biennis from a long-term polluted site. Environ Sci Pollut Res Int 24(24):19640–19652. https://doi.org/10.1007/s11356-017-9496-1
Park JM, Hong JW, You Y-H, Kim J-G (2021) Endophytic fungi of emersed halophytes in river deltas and tidal flats of the Korean Ramsar wetlands. J Mar Sci Eng 9:430. https://doi.org/10.3390/jmse9040430
Pathan SI, Ceccherini MT, Sunseri F, Lupini A (2020) Rhizosphere as hotspot for plant-soil-microbe interaction. In: Datta R, Meena RS, Pathan SI, Ceccherini MT (eds) Carbon and Nitrogen Cycling in Soil. Springer, Singapore, pp 17–43
Parzych A, Cymer M, Macheta K (2016) Leaves and roots of Typha latifolia L. and Iris pseudacorus L. as bioindicators of contamination of bottom sediments by toxic elements. Limnol Rev 16(2):77–83. https://doi.org/10.1515/limre-2016-0008
Pérez-Jaramillo J, Carrión EVJ, de Hollander M, Raaijmakers JM (2018) The wild side of plant microbiomes. Microbiome 6:143. https://doi.org/10.1186/s40168-018-0519-z
Peršoh D (2015) Plant-associated fungal communities in the light of meta’omics. Fungal Diversity 75(1):1–25. https://doi.org/10.1007/S13225-015-0334-9
Pietrangelo L, Bucci A, Maiuro L, Bulgarelli D, Naclerio GG (2018) Unravelling the composition of the root associated, bacterial microbiota of Phragmites australis and Typha latifolia. Front Microbiol 9:1650–1662. https://doi.org/10.3389/2Ffmicb.2018.01650
Prado C, Chocobar-Ponce S, Pagano E, Prado F, Rosa M (2021) Differential effects of Zn concentration on Cr (IV) uptake by two Slvinia species: involvement of thiol compounds. Intl J Phytoremediation 23(1):10–17. https://doi.org/10.1080/15226514.2020.1786796
Prasad MNV (2003) Phytoremediation of metal-polluted ecosystems: hype for commercialization. Russ J Plant Physiol 50:686–701. https://doi.org/10.1023/A:1025604627496
Purwanti IF, Kurniawan SB, Titah HS, Tangahu BV (2018) Identification of acid and aluminium resistant bacteria isolated from aluminium recycling area. Int J Civ Eng Technol 9:945–954. http://www.iaeme.com/ijciet/issues.asp?JType=IJCIETandVType=9andIType=2. Accessed 11 June 2023
Purwanti IF, Obenu A, Tangahu BV, Kurniawan SB, Imron MF, Abdullah SRS (2020) Bioaugmentation of Vibrio alginolyticus in phytoremediation of aluminium-contaminated soil using Scirpus grossus and Thypa angustifolia. Heliyon 6(9):e05004. https://doi.org/10.1016/j.heliyon.2020.e05004
Purwanti IF, Kurniawan SB, Imron MF (2019) Potential of Pseudomonas aeruginosa isolated from aluminium-contaminated site in aluminium removal and recovery from wastewater. Environ Technol Innov 15:100422. https://doi.org/10.1016/j.heliyon.2020.e05004
Qin L, Jiang M, Tian W, Zhang J, Zhu W (2017) Effects of wetland vegetation on soil microbial composition: a case study in Tumen River Basin, Northeast China. Chin Geogr Sci 27:239–247. https://doi.org/10.1007/s11769-017-0853-2
Qiao K, Wang F, Liang S, Wang H, Hu Z, Chai T (2019) Improved Cd, Zn and Mn tolerance and reduced Cd accumulation in grains with wheat-based cell number regulator TaCNR2. Sci Rep 9:1–10. https://doi.org/10.1038/s41598-018-37352-6
Rajendran SK, Sundaram L (2020) Degradation of heavy metal contaminated soil using plant growth promoting rhizobacteria (PGPR): Assess their remediation potential and growth influence of Vigna radiata L. Intl J Agri Technol 16(2):365–376. http://www.ijat-aatsea.com. Accessed 12 June 2023
Rajkumar M, Ae N, Prasad MN, Freitas H (2010) Potential of siderophore-producing bacteria for improving heavy metal phytoextraction. Trends Biotechnol 28(3):142–149. https://doi.org/10.1016/j.tibtech.2009.12.002
Rajkumar M, Sandhya S, Prasad MNV, Freitas H (2012) Perspectives of plant-associated microbes in heavy metal phytoremediation. Biotechnol Adv 30(6):1562–1574. https://doi.org/10.1016/J.BIOTECHADV.2012.04.011
Rascio N, Navari-Izzo F (2011) Heavy metal hyperaccumulating plants: how and why do they do it? and What makes them so interesting? Plant Sci 180:169–181. https://doi.org/10.1016/j.plantsci.2010.08.016
Rashid M, Ahmad I, Ashique MA, Mahmood Ul, Hassan MU (2020) Phytoremediation of battery industry effluent through aquatic macrophytes. Intl J Bio Res 8(1):6–16. https://doi.org/10.14419/ijbr.v8i1.31145
Raza A, Razzaq A, Mehmood SS, Zou X, Zhang X, Lv Y, Xu J (2019) Impact of climate change on crops adaptation and strategies to tackle its outcome: a review. Plants 8(2):34. https://doi.org/10.3390/plants8020034
Reichman SM, Parker DR (2005) Metal complexation by phytosiderophores in the rhizosphere. Biogeochemistry of trace elements in the rhizosphere. Elsevier, pp 129–156
Rezania S, Taib SM, Din MF, Dahalan FA, Kamyab H (2016) Comprehensive review on phytotechnology: Toxic elements removal by diverse aquatic plants species from wastewater. J Hazard Mater 318:587–599. https://doi.org/10.1016/j.jhazmat.2016.07.053
Robertson C, Clothier B, Sivakumarana S, McLachlana A, McIvor I, Meikle H (2012) Nitrogen management by watercress (Nasturtium officinale) in hydroponic conditions. https://www.yumpu.com/en/document/read/11275975/nitrogen-management-by-watercress-massey-university. Accessed: 20 June 2023
Rojas LA, Yanez C, Gonzalaez M, Lobos S, Smalla K, Seeger M (2011) Characterisaton of the metabolically modified heavy-metal resistant Cupriavidus meetallidurans strain MSR33 generated for mercury remediation. PLoS One 6(3):1–10. https://doi.org/10.1371/journal.pone.0017555
RoyChowdhury A, Datta R, Sarkar D (2018) Heavy metal pollution and remediation. In: Török B, Dransfield T (eds) Green chemistry. Elsevier, pp 359–373
Safronova VI, Stepanok VV, Engqvist GL, Alekseyev YV, Belimov AA (2006) Root-associated bacteria containing 1- aminocylopropane-1-carboxylate deaminase improve growth and nutrient uptake by pea genotypes cultivated in cadmium supplemented soil. Bio Fertil Soils 42(3):267–272. https://doi.org/10.1007/s00374-005-0024-y
Saha P, Shinde O, Sarkar S (2017) Phytoremediation of industrial mines wastewater using water hyacinth. Intl J Phytoremediation 19:87–96. https://doi.org/10.1080/15226514.2016.1216078
Sakakibara M (2016) Phytoremediation of toxic elements-polluted water and soils by aquatic macrophyte Eleocharis acicularis. AIP Conf Proc 1744(020038):1–6. https://doi.org/10.1063/1.4953512
Saleh MY, El-Enany G, El-Zehar MM, Omran MH (2015) Industrial wastewater treatment improvements using activated carbon [Paper presention]. ICEEESD March 2015: Intl Conf Energy Ecol Environ Sust Develop, Miami, FL, United States
Sand-Jensen K, Prabl C, Stokohlm H (1982) Oxygen release from roots of submerged aquatic macrophytes. Oikos 38:349–354. https://doi.org/10.2307/3544675
Sauvêtre A, Wegrzyn A, Yang L, Vestergaard G, Miksch K, Schröder P, Radl V (2020) Enrichment of endophytic actinobacteria in roots and rhizomes of miscanthus _ giganteus plants exposed to diclofenac and sulfamethoxazole. Environ Sci Pollut Res Int 27:11892–11904. https://doi.org/10.1007/s11356-020-07609-7
Saggaï MM, Ainouche A, Nelson M, Cattin F, El Amrani A (2017) Long-term investigation of constructed wetland wastewater treatment and reuse: selection of adapted plant species for metaremediation. J Environ Manag 201:120–128. https://doi.org/10.1016/j.jenvman.2017.06.040
Schalk IJ, Hannauer M, Braud A (2011) New roles for bacterial siderophores in metal transport and tolerance. Environ Microbiol 13(11):2844–2854. https://doi.org/10.1111/j.1462-2920.2011.02556.x
Schmidt R, Ulanova D, Wick LY, Bode HB, Garbeva P (2019) Microbe-driven chemical ecology: past, present and future. ISME J 13:2656–2663. https://doi.org/10.1038/s41396-019-0469-x
Sehar S, Nasser HAA (2019) Wastewater treatment of food industries through constructed wetland: a review. IJEST 16:6453–6472. https://doi.org/10.1007/s13762-019-02472-7
Schor-Fumbarov T, Zvika K, Elisha T-O (2003) Characterisation of cadmium uptake by the water lily Nymphaea aurora. Int J Phytoremediation 5:169–179. https://doi.org/10.1080/713610178
Seward J, Crson MA, Lamit L, Basiliko N, Yavitt JB, Lilleskov E, Schadt CW, Smith DS, Mclaughin J, Mykytcuzuk NCS, Williams ST, Roulet N, Moore T, Harris L, Brauer SL (2020) Peatland microbial community composition is driven by a ntural climate gradient. Microb Ecol 80(3):593–602. https://doi.org/10.1007/s00248-020-01510-z
Shahid, AL-surhanee AJ, Kouadri AA, Ali F, Nawaz S, Afzal N, Rizwan M, Ali M, Soliman B, Mona H (2020) Role of microorganisms in the remediation of wastewater in floating treatment wetlands: a review. Sustainability 12(14):5559.https://doi.org/10.3390/su12145559
Shaikh SS, Wani SJ, Sayyed RZ (2018). Impact of interactions between rhizosphere and rhizobacteria: a review. J Bacteriol Mycol 5(1):1058. https://austinpublishinggroup.com/bacteriology/fulltext/bacteriology-v5-id1058.php. Accessed 16 June 2023
Shehzadi M, Imran A, Mirza MS, Khan QM, Afzal M (2016) Ecology of bacterial endophytes associated with wetland plants growing in textile effluent for pollutant-degradation and plant growth-promotion potentials. Plant Biosyst 150(6):1261–1270. https://doi.org/10.1080/11263504.2015.1022238
Sheoran V, Sheoran AS, Poonia P (2011) Role of hyperaccumulators in phytoextraction of metals from contaminated mining sites: a review. Crit Rev Environ Sci Technol 41(2):168–214. https://doi.org/10.1080/10643380902718418
Shi X, Meng X, Liu G, Juang Y, Liu S, Houe C, Meng Q, Xu H (2016) Annual variation of protozoan communities and its relationship to environmental conditions in a sub-tropic urban wetland ecosystem, southern China. Protistology 9(3/4):133–142
Singh P, Pani A, Mujumdar AS, Shirkole SS (2023) New strategies on the application of artificial intelligence in the field of phytoremediation. Int J Phytoremediation 25(4):505–523. https://doi.org/10.1080/15226514.2022.2090500
Sood AU, Prasanna PL, Ahluwalia R, Amrik S (2011) Phytoremediation potential of aquatic macrophyte, Azolla. AMBIO 41(2):122–137. https://doi.org/10.1007/2Fs13280-011-0159-z
South Africa. Government Notice: Department of environment, forestry and fisheries (2020) Alien and invasive species regulations (Act No. 10 of 2004). Government Gazette No. 43735. www.gpwonline.co.za. Accessed 22 June 2023
South African Nursery Association (SANA) (2018) Invasive alien plants- CARA list [Online] 16 June, 2013. Available: http://sana.co.za/2013/01/16/invasive-alien-plants/ Accessed: 24 June 2023
Stefanakis AI, Akratos CA, Tsihrintzis VA (2014) Vertical flow constructed wetlands: eco-engineering systems for wastewater and sludge treatment. Elsevier, Amsterdam, Netherlands, p 332
Stefanakis AI (2018) Constructed Wetlands for Industrial Wastewater, treatment. Wiley Ltd, UK
Steinle P, Thalmann P, Höhener P, Hanselmann KW, Stucki G (2000) Effect of environmental factors on the degradation of 2,6-dichlorophenol in soil. Environ Sci Technol 34(5):771–775. https://doi.org/10.1021/es990587l
Suyamud B, Thiravetyan P, Gadd GM, Panyapinyopol B, Inthorn D (2020) Bisphenol A removal from a plastic industry wastewater by Dracaena sanderiana endophytic bacteria and Bacillus cereus NI. Intl J Phytoremediation 22(2):167–175. https://doi.org/10.1080/15226514.2019.1652563
Sun JL, Zeng H, Ni HG (2013) Halogenated polycyclic aromatic hydrocarbons in the environment. Chemosphere 90(6):1751–1759. https://doi.org/10.1016/j.chemosphere.2012.10.094
Sun K, Liu J, Jin J, Gao Y (2014) Utilizing pyrene-degrading endophytic bacteria to reduce the risk of plant pyrene contamination. Plant Soil 374:251–262. https://doi.org/10.1007/s11104-013-1875-x
Sun B, Zhang X, Yin Y, Sun H, Ge H, Li W (2017) Effects of sulforaphane and vitamin E on cognitive disorder and oxidative damage in lead-exposed mice hippocampus at lactation. J Trace Elem Med Biol 44:88–92. https://doi.org/10.1016/j.jtemb.2017.06.004
Supreeth M (2022) Enhanced remediation of pollutants by microorganisms–plant combination. Intl J Environ Sci Technol 19(5):4587–4598. https://doi.org/10.1007/2Fs13762-021-03354-7
Syranidou E, Christofilopoulos S, Gkavrou G, Thijs S, Weyens N, Vangronsveld J, Kalogerakis N (2016) Exploitation of endophytic bacteria to enhance the phytoremediation potential of the wetland helophyte Juncus acutus. Front Microbiol 7:10–16. https://doi.org/10.3389/2Ffmicb.2016.01016
Syranidou E, Thijs S, Avramidou M, Weyens N, Venieri D, Pintelon I, Vangronsveld J, Kalogerakis N (2018) Responses of the endophytic bacterial communities of Juncus acutus to pollution with metals, emerging organic pollutants and to bioaugmentation with indigenous strains. Front Plant Sci 9(1526):1–14. https://doi.org/10.3389/fpls.2018.01526
Szabó-Tugyi N, Tóth VR (2020) Interaction among bacterioplankton and macrophytes in shallow lakes with high macrophyte cover. Aquat Sci 82(79). https://doi.org/10.1007/s00027-020-00753-9
Tadesse AT, Seyoum LA (2015) Evaluation of selected wetland plants for removal of chromium from tannery wastewater in constructed wetlands, Ethiopia. Afr J Environ Sci Technol 9:420–427. https://doi.org/10.5897/AJEST2014.1793
Thakur SS, Lakhveer W, AbS Z, Muhammad FA, Samson MD, Mohd F (2016) Plant-driven removal of toxic elements from soil: uptake, translocation, tolerance mechanism, challenges, and future perspectives. Environ Mon Assess 188(4):1–11. https://doi.org/10.1007/s10661-016-5211-9
Thangavel P, Subbhuraam CV (2004) Phytoextraction: role of hyperaccumulators in metal contaminated soils. Proc Indian Natl Sci Acad Part B 70:109–130.https://doi.org/10.1080/10643380902718418
Thion C, Cébron A, Beguiristain T, Leyval C (2013) Inoculation of PAH-degrading strains of Fusarium solani and Arthrobacter oxydans in rhizospheric sand and soil microcosms: microbial interactions and PAH dissipation. Biodegradation 24(4):569–581. https://doi.org/10.1007/s10532-013-9628-3
Thomaz SM, Mormul RP, Michelan TS (2015) Propagule pressure, invisibility of freshwater ecosystems by macrophytes and their ecological impacts: a review of tropical freshwater ecosystems. Hydrobiologia 74:39–59. https://doi.org/10.1007/s10750-014-2044-9
Tirry N, Kouchou A, Omari BE, Ferioun M, Ghachtouli NE (2021) Improved chromium tolerance of Medicago sativa by plant growth-promoting rhizobacteria (PGPR). J Gen Engin Biotechnol 19(149):1–14. https://doi.org/10.1186/s43141-021-00254-8
Toju H, Peay KG, Yamamichi M, Narisawa K, Hiruma K, Naito K, Fukuda S, Ushio M, Nakaoka S, Onoda Y, Yoshida K, Schlaeppi K, Bai Y, Sugiura R, Ichihashi Y, Minamisawa K, Kiers E (2018) Core microbiomes for sustainable agroecosystems. Nat Plants 4(5):247–257. https://doi.org/10.1038/s41477-018-0139-4
Toyama T, Furukawa T, Maeda N, Inoue D, Sei K, Mori K, Kikuchi S, Ike M (2011) Accelerated biodegradation of pyrene and benzo[a]pyrene in the Phragmites australis rhizosphere by bacteria-root exudate interactions. Water Res 45:1629–1638. https://doi.org/10.1016/j.watres.2010.11.044
Ullah A, Heng S, Munis MFH, Fahad S, Yang X (2015) Phytoremediation of toxic elements assisted by plant growth promoting (PGP) bacteria: a review. Environ Exp Bot 117:28–40. https://doi.org/10.1016/j.envexpbot.2015.05.001
Vamerali T, Bandiera M, Mosca G (2010) Field crops for phytoremediation of metal-contaminated land: a review. Environ Chem Lett 8:1–17. https://doi.org/10.1007/s10311-009-0268-0
Verma R, Anupama A, Singh AK, Prasad S (2017) An arginine functionalized magnetic nano-sorbent for simultaneous removal of three metal ions from water samples. RSC Adv 7(81):51079–51089. https://doi.org/10.1039/C7RA09705K
Visioli G, Vamerali T, Mattarozzi M, Dramis L, Sanangelantoni AM (2015) Combined endophytic inoculants enhance nickel phytoextraction from serpentine soil in the hyperaccumulator Noccaea caerulescens. Front Plant Sci 6:638. https://doi.org/10.3389/fpls.2015.00638
Vymazal J, Kröpfelová L (2008) Wastewater treatment in constructed wetlands with horizontal sub-surface flow. Environ Pollut 14, Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-8580-2_4
Vymazal (2007) Removal of nutrients in various types of constructed wetlands. Sci Total Environ 380:48–65. https://doi.org/10.1016/j.scitotenv.2006.09.014
Vystavna Y, Frkova Z, Marchand L, Vergeles Y, Stolberg F (2017) Removal efficiency of pharmaceuticals in a full scale constructed wetland in East Ukraine. Ecol Eng 108:50–58. https://doi.org/10.1016/j.ecoleng.2017.08.009
Wang Y, Li H, Zhao W, He X, Chen J, Geng X, Xiao M (2010) Induction of toluene degradation and growth promotion in corn and wheat by horizontal gene transfer within endophytic bacteria. Soil Biol Biochem 42(7):1051–1057. https://doi.org/10.1016/j.soilbio.2010.03.002
Wang HW, Zhang W, Su CL, Zhu H, Dai CC (2015) Biodegradation of the phytoestrogen luteolin by the endophytic fungus Phomopsis liquidambari. Biodegradation 26(3):197–210. https://doi.org/10.1007/s10532-015-9727-4
Wang Y, Tian H, Huang F, Long W, Zhang Q, Wang J, Zhu Y, Wu X, Chen G, Zhao L, Bakken LR, Frostegård Å, Zhang X (2017) Time-resolved analysis of a denitrifying bacterial community revealed a core microbiome responsible for the anaerobic degradation of quinoline. Sci Rep 7(1). https://doi.org/10.1038/s41598-017-15122-0
Wang J, Liu J, Ling W, Huang Q, Gao Y (2017b) Composite of PAH-degrading endophytic bacteria reduces contamination and health risks caused by PAHs in vegetables. Sci Total Environ 598:471–478. https://doi.org/10.1016/j.scitotenv.2017.04.126
Wang F, Jing X, Adams CA, Shi Z, Sun Y (2018) Decreased ZnO nanparticple phytotoxicty to maize by arbuscrular mycorrhizal fungus organic phosphorus. ESPR 25:23736–23747. https://doi.org/10.1007/s11356-018-2452-x
Wang R, Cui L, Li J, Li W (2023) Factors driving the halophyte rhizosphere bacterial communities in coastal salt marshes. Front Microbiol 14:1127958. https://doi.org/10.3389/fmicb.2023.1127958
Westlake DF (1965) Some basic data for investigations of the productivity of aquatic macrophytes. In Primary productivity in aquatic environments. University of California Press
Weyens N, Schellingen K, Beckers B, Janssen J, Ceulemans R, Lelie D, Taghavi S, Carleer R, Vangronsveld J (2013) Potential of willow and its genetically engineered associated bacteria to remediate mixed Cd and toluene contamination. J Soils Sed 13:176–188. https://doi.org/10.1007/s11368-012-0582-1
Whiting SN, Leake JR, McGrath SP, Baker AJ (2001) Hyperaccumulation of Zn by Thlaspi caerulescens can ameliorate Zn toxicity in the rhizosphere of cocropped Thlaspi arvense. Environ Sci Technol 15:3237–3241. https://doi.org/10.1021/es010644m
Wu G, Kang H, Zhang X, Shao H, Chu L, Ruan C (2010) A critical review on the bio-removal of hazardous toxic elements from contaminated soils: issues, progress, eco-environmental concerns and opportunities. J Hazard Mater 174(1–3):1–8. https://doi.org/10.1016/j.jhazmat.2009.09.113
Wu T, Xu J, Liu J, Guo W-H, Li X-B, Xia J-B, Xie W-J, Yao Z-G, Zhang Y-M, Wang R-Q (2019) Characterization and initial application of endophytic Bacillus Safensis Strain ZY16 for Improving phytoremediation of oil-contaminated saline soils. Front Microbiol 10(991). https://doi.org/10.3389/fmicb.2019.00991
Xie XG, Dai CC (2015) Degradation of a model pollutant ferulic acid by the endophytic fungus Phomopsis liquidambari. Bioresour Technol 179:35–42. https://doi.org/10.1016/j.biortech.2014.11.112
Xie F, Ma A, Zhou H, Liang Y, Yin J, Ma K, Zhuang X, Zhuang G (2020) Revealing fungal communities in alpine wetlands through species diversity, functional diversity and ecological network diversity. Microorganisms 8(5):632. https://doi.org/10.3390/microorganisms8050632
Xin J, Ma S, Li Y, Zhao C, Tian R (2020) Pontederia cordata, an ornamental aquatic macrophyte with great potential in phytoremediation of heavy-metal contaminated wetlands. Ecotoxicol Environ Safe 203:111–124. https://doi.org/10.1016/j.ecoenv.2020.111024
Xiong C, Zhu YG, Wang JT, Singh B, Han LL, Shen JP, Li PP, Wang GB, Wu CF, Ge AH, Zhang LM, He JZ (2021) Host selection shapes crop microbiome assembly and network complexity. New Phytol 29(2):1091–1104. https://doi.org/10.1111/nph.16890
Yadav BK, Akhtar MS, Panwar J (2015) Rhizospheric plant-microbe interactions: key factors to soil fertility and plant nutrition. In: Arora NK (ed) Plant microbes symbiosis: applied facets. Springer, India, pp 127–145
Yin X, Lu J, Wang Y, Liu G, Hua Y, Wan X, Zhao J, Zhu D (2020) The abundance of nirS-type denitrifiers and anammox bacteria in rhizospheres was affected by the organic acids secreted from roots of submerged macrophytes. Chemosphere 240:124903. https://doi.org/10.1016/j.chemosphere.2019.124903
Yousaf S, Afzal M, Reichenauer TG, Brady CL, Sessitsch A (2011) Hydrocarbon degradation, plant colonization and gene expression of alkane degradation genes by endophytic Enterobacter ludwigii strains. Environ Pollut 159:2675–2683. https://doi.org/10.1016/j.envpol.2011.05.031
Yu S, Teng C, Bai X, Liang J, Song T, Dong L, Jin Y, Qu J (2017) Optimization of Siderophore Production by Bacillus sp. PZ-1 and Its Potential Enhancement of Phytoextration of Pb from Soil. J Microbiol Biotechnol 27:1500–1512. https://doi.org/10.4014/jmb.1705.05021
Zahoor M, Irshad M, Rahman H, Qasim M, Afridi SG, Qadir M, Hussain A (2017) Alleviation of heavy metal toxicity and phytostimulation of Brassica campestris L. by endophytic Mucor sp. MHR-7. Ecotoxicol Environ Safe 142:139–149. https://doi.org/10.1016/j.ecoenv.2017.04.005
Zhalnina K, Louie KB, Hao Z, Mansoori N, Da Rocha UN, Shi S, Cho H, Karaoz U, Loqué D, Bowen BP (2018) Dynamic root exudate chemistry and microbial substrate preferences drive patterns in rhizosphere microbial community assembly. National Microbiol 3(4):470–480. https://doi.org/10.1038/s41564-018-0129-3
Zhang JW, Fang Z, Gregg BM, Schumann, (1997) Carbon isotopic composition, gas exchange, and growth of three populations of ponderosa pine differing in drought tolerance. Tree Physiol 17:461–466. https://doi.org/10.1093/treephys/17.7.461
Zhang S, Zhang Z, Xia S, Ding N, Liao X, Yang R, Chen M, Chen S (2021) The potential contributions to organic carbon utilization in a stable acetate-fed Anammox process under low nitrogen-loading rates. Sci Total Environ 784:147150. https://doi.org/10.1016/j.scitotenv.2021.147150
Zhang H, Zhang L-L, Li J, Chen M, An R-D (2020) Comparative study on the bioaccumulation of lead, cadmium and nickel and their toxic effects on the growth and enzyme defence strategies of a heavy metal accumulator Hydrilla verticillatat (L.f.) Royle. Environ Sci Pollut Res-Intl 27(9):9853–9865. https://doi.org/10.1007/s11356-019-06968-0
Zhang G, Jia J, Zhao Q, Wang W, Wang D, Bai J (2023) Seasonality and assembly of soil microbial communities in coastal salt marshes invaded by a perennial grass. J Environ Manage 331:117247. https://doi.org/10.1016/j.jenvman.2023.117247
Zhu T, Sikora FJ (1995) Ammonium and nitrate removal in vegetated and unvegetated gravel bed microcosm wetlands. Water Sci Technol 32:219–228. https://doi.org/10.1016/0273-1223(95)00623-0
Zhu X, Ni X, Waigi MG, Liu J, Sun K, Gao Y (2016) Biodegradation of Mixed PAHs by PAH-Degrading Endophytic Bacteria. Int J Environ Res Public Health 13(8):805. https://doi.org/10.3390/2Fijerph13080805
Zhu S, Shi W, Jie Y (2021) Overexpression of BnPCS1, a Novel Phytochelatin synthase gene from ramie (boehmeria nivea), enhanced cd tolerance, accumulation, and translocation in Arabidopsis thaliana. Front Plant Sci 12:639189. https://doi.org/10.3389/fpls.2021.639189
Acknowledgements
The authors wish to acknowledge the immense assistance consistently provided by Ms. Ramaisimela Dolly Mazwi as an administrative staff of the University of South Africa.
Funding
Open access funding provided by University of South Africa. This research received no direct funding.
Author information
Authors and Affiliations
Contributions
G.N.I. conceptualized the research; the original draft preparation was executed by T.L and T.M; manuscript draft edits and improvement was done by G.N.I. Final draft edit was done by T.N.M. All authors contributed to the several drafts' corrections and editing to achieve a final draft. All authors have read and agreed to the published version of the manuscript.
Corresponding author
Ethics declarations
Conflicts of interest
The authors declare no conflict of interest.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Ijoma, G.N., Lopes, T., Mannie, T. et al. Exploring macrophytes’ microbial populations dynamics to enhance bioremediation in constructed wetlands for industrial pollutants removal in sustainable wastewater treatment. Symbiosis 92, 323–354 (2024). https://doi.org/10.1007/s13199-024-00981-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13199-024-00981-9