Impact of Hydrocarbons on Marine Microbial Communities

Abstract

The coastal areas are periodically exposed to pollution by crude oil, in a chronic or accidental way. This leads to a rupture of the equilibrium of the bacterial communities in the coastal ecosystems. In other respects, the important metabolic diversity present in these ecosystems suggests an important enzymatic potential for hydrocarbon degradation. We intend to evaluate the impact of oil pollution on coastal bacterial communities and the biodegradation potential. Analyses of bacterial communities by molecular approaches allowed the characterization of the structure and the dynamic of these communities in chronic polluted sites (mats of Berre Lagoon, Provence, France) or in punctually contaminated laboratory microcosms (mats of Salins-de-Giraud, Camargue, France; sediments of the Benoit aber, Bretagne, France). Genomic and transcriptomic T-RFLP (Restriction Fragment Length Polymorphism) analysis based on 16S rRNA encoding genes showed changes in bacterial diversity and community structures revealing the adaptation of microorganisms to oil pollution. Identification of naturally occurring differences between unpolluted and polluted microbial communities' transcriptomes have also been demonstrated by the differential display method. Several functional bacterial mRNA were characterized as differentially expressed according to experimental conditions. The role of these genes in the response of hydrocarbon must be elucidated. We also develop an approach to characterize adaptive genes associated to mobile elements.