Molecular Biology of microorganisms capable of degrading pollutants
Chemical products released from industrial, agricultural, municipal and domestic activities have contaminated several areas during the last decades and have created important pollution problems. Several compounds such as aromatic molecules have mutagenic, teratogenic and/or carcinogenic properties. Conventional methods of decontamination or storage are expensive and not efficient, causing an urgent need of new methods. Degradation of these products by microorganisms offers a promising approach to decontaminate polluted sites.
It was shown that several bacterial strains and several bacterial consortium are capable, in aerobic or anaerobic conditions, to degrade different aromatic compounds such as chlorophenols, polychlorinated biphenyl (PCB), phenolic compounds and polycyclic aromatic hydrocarbons (PAH). These bacteria use different biochemical pathways to cleave the benzenic rings; the resulting molecules being more easily assimilated.
Our group has isolated several aerobic and anaerobic bacterial strains capable of degrading aromatic compounds. One of our objectives is to characterize genes encoding for enzymes involved in the degradation of aromatic compounds by studying their chromosomic arrangement, their sequence and their expression. Furthermore, we studied the gene products for their enzymatic properties and their structures.
Study of microbial diversity in bioprocesses
Several types of biological processes have been developed to treat contaminated soil/sediments, liquid effluents and exhausted air. Although physico-chemical parameters can be easily controlled by engineers, the understanding of what happens inside these bioprocesses often remains unclear. For instances, what kind of microorganisms are implicated in these bioprocesses, and what are their abundance and their physiological states are still unanswered questions. How the microbial population evolves during the ongoing process, and how it responds to different conditions or stresses remain to be determined. Finally, the spatial organization of microorganisms and the interactions occurring between each type of microorganisms and with the support need to be understood.
The majority of bioprocesses operates with complex and uncharacterized microbial communities. Research on the ecology of these communities is impaired by a lack of tools to analyse microorganisms which cannot be cultivated. Culture methods may favor fast-growing microorganisms that have not numerical or ecological importance in a process. The use of non-culturable approaches with molecular tools provides a more accurate evaluation of a microbial community.
Our research aims to evaluate the dynamics of microbial communities associated with biological processes of depollution with molecular tools. We use these tools to identify microorganisms (with the ribosomal gene sequences) present in the bioprocesses and to develop specific DNA probes for the detection and the monitoring of these microorganisms by fluorescent in situ hybridization. With epifluorescent and confocal microscopy, it is now possible to visualize specific microorganisms directly in their environment, for example, in biofilms.
This research will increase our fundamental knowledge by knowing how microorganisms participate in the studied bioprocesses. Combined with physico-chemical parameters, it will allow engineers to generate a more accurate modelization of the bioprocesses, leading on a better design and improvement of larger-scale bioprocesses. For example, it will allow early and precise diagnostics of some operational problems.
Dr. Richard Villemur, Ph.D. (Biochemistry, Université de Montréal, ; postdoctoral studies at the National Research Council of Canada in Halifax [1987-1989] and at the University of Minnesota [1990-1993]) is a professor at INRS-Institut Armand-Frappier since 1993. His is the specialist in molecular biology for the Groupe de Recherche en Microbiologie de l'Environnement at INRS-Institut Armand-Frappier.
The Research Group on Environmental Microbiology is seeking Master and PhD candidates. For more details see our web site at http://www.microbio-environnement.org
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