Toward inline multiplex biodetection of metals, bacteria, and toxins in water networks: the COMBITOX project
- 950 Downloads
This special issue of Environmental Science and Pollution Research highlights selected papers whose results have been obtained in the course of the COMBITOX project. COMBITIOX is an interdisciplinary research project funded by the French National Research Agency (ANR) aiming at conceiving an inline multiparametric device for the surveillance of water networks using biosensors. This device is not intended to fully replace chemical methods, but when compared to analytical chromatographic methodologies, biological sensors can offer rapid and on-site monitoring of even trace levels of targeted compounds (Sun et al. 2015) and can quickly raise the alarm in the event of an accidental or intentional pollution. Numerous developments have been published to improve the sensitivity, specificity, and time response of various biosensors in laboratory conditions (Xiong et al. 2012) (der Meer et al. 2010), but their actual transfer into technological devices for the surveillance of water networks remains at a conceptual level. Thus, the challenge here is to go a step beyond and validate biosensors under real-life field conditions by incorporating them in a single inline detector. During the course of COMBITOX, we could define the interface between the biosensors and a common light detector as well as the physical conditioning of the bioreagents and usage protocol. Our resulting prototype allow the detection of bioavailable toxic compounds as well as microorganisms, impacting human health through the drinking water network or interfering with the biological process of modern wastewater treatment plants. We also plan to propose this system to meet the emerging threats such as bioterrorism.
COMBITOX focuses on three families of “objects” to detect: metals (cadmium, mercury, arsenic, nickel, etc.), environmental and/or food toxins, and pathogenic microorganisms. Whole-cell biosensors based on reporter gene under the control of an inducible promoter are used to detect various metals (Hynninen and Virta 2010), the antibody/antigen interaction for toxins (Makaraviciute and Ramanaviciene 2013), and the specific infection of bacteria by bacteriophages for pathogenic microorganisms (Smartt et al. 2012) (Vinay et al. 2015). In all cases, the signal measured is photochemical (fluorescence, bio-luminescence, or chemo-luminescence): such a method to transduce the biological recognition is very sensitive and a single photodetector can be used for all biosensors included in the device. The challenge here rather lies in the design and the optimization of the different biological compounds for their use in the field while maintaining a high sensibility and robustness. As a consequence, the different articles presented in this special issue focus on original strategies for the optimization and the adaptation of the three types of biosensors for their use in a semi-autonomous inline water analyzer. In the case of whole-cell biosensors, improvement of the dose-responses and the specificity by genetic modifications of the regulators is exemplified for a nickel bioluminescent biosensor (Cayron et al. in this special issue). The key-issue of the biosensor conservation over a period of time compatible with the autonomy of the device requested by the end-user while maintaining a satisfactory sensitivity, specificity, and time response is also addressed (Prévéral et al. in this special issue). Moreover, Brutesco et al. characterized an original near-infrared fluorescent reporter candidate that represents an interesting alternative to bacterial luciferase to perform biodetection in turbid and complex water samples. The use of a robust environmental bacterial species (Deinococcus deserti) as cellular chassis is also shown to correspond to an interesting alternative to laboratory Escherichia coli stains for optimal biodetection out of the laboratory benches while offering desiccation as a cost-effective solution to the problem of biosensors long-term storage. Last but not least, transferring biosensors into Deinococcus species open the field of metallic radioisotopes (Brutesco et al. in this special issue). In addition, the strategy used and validated for the implementation of immunodetectors in our automatous inline analyzer is based on the development of chitosan support for oriented immobilization of functionally intact polyclonal antibodies (Demey et al. in this special issue). Phage-based biodetectors using a luminescent and substrate independent output to detect different E. coli strains have also been developed and tailored to our analyzer (Franche et al. in this special issue). Taken together, these different studies contribute to reach our major objective of using various types of biosensor in an autonomous inline prototype, whose elaboration of the light detector/incubation chamber as well as the procedures to bring the three types of biosensors into play are also described in this special issue (Descamps et al.). The COMBITOX project provides the proof of concept that biosensors can be used in the field to detect different targets (As, Hg, Ni as metals, microcystin as a toxin model, and E. coli for bacteria detection). This list could easily be extended in the future to respond to requests of putative clients and meet the societal challenges of environmental survey.
Authors and reviewers are greatly acknowledged for their contributions. Dr. Philippe Garrigues, Editor-in-Chief of Environmental Science and Pollution Research and his Editorial team are warmly thanked for their interest on this topic and handling of the review process.