Combatting Plastic Pollution in Natural Environments: Innovative Solutions Offered by Microbes

Abstract

Plastic pollution is one of the most bothersome issues mankind is facing in the modern era because we cannot completely do away with the plastics, nor do we have enough solutions for the heaps of plastics littering our land and seas in microplastic (MP) and nanoplastic forms also. As methods for identification and measurement of microplastics in different ecosystems are developing, there is growing concern about its possible consequences on micro and macroflora, and fauna. The persistence of microplastics (MPs) and their possible negative effects on biota make MP pollution a serious environmental issue. However, as the plastic mounds increased and continued to accumulate in the environment, nature found its own way of fighting back. The so called “non-biodegradable” material was found to be broken down by none other than the tiniest creatures on earth. In response to the manmade plastic hazard, microbes have evolved the capacity to enzymatically degrade the recalcitrant polymers. Literature shows several strains of microorganisms can mineralize plastics but the diversity of microbes involved in this activity and the extent of mineralization is practically unknown. Majority of scientific investigations have focused on MP dispersion, ingestion, destiny, behaviour, quantity, and effects; but few studies report the techniques for MP removal and remediation. Therefore, in this chapter we propose to explore the practical possibility of microbial communities in the remediation of plastics in contaminated sites of land and water bodies, and report microbial strains/consortia that can degrade different types of microplastics like Polypropylene (PP), Polyethylene (PE), Polyetheylene Terepthalate (PETE), High Density Polyethylene (HDPE), and Low-Density Polyethylene (LDPE). The sources and effects of MPs, and its impact on human health are examined. The most recent research and developments in the enzymatic properties of microorganisms, and the mechanisms of biodegradation by bacteria and fungi, in consortia or biofilms, are discussed. The influence of temperature, pH, nutrient availability, and microbial competition, on the biodegradation; and finally the products of biodegradation and the molecular methods or other instrumental techniques of characterizations of plastic degradation are also elaborated. The plastic degradation by invertebrates is also covered because there are several reports of worms and insects that eat plastics. Unique methods for the biodegradation of microplastics must be developed to understand the various ways in which microbes react to these plastic contaminants, in order to lessen their negative effects on the environment. Still, a lot of microbial mechanisms involved in the enzymatic degradation pathway of plastics remain to be elucidated.