Degradation of the

Since March 2001, samples of the remaining oil from the wreck of the “Erika” have been collected along the Atlantic coastline in order to assess the natural degradation rate. Four years after the sinking of the tanker, chemical analyses of the oil revealed the influence of environmental parameters on the degradation kinetics. Among the diverse parameters controlling the fate of oil in the environment, biodegradation by microorganisms is known to play an important role. To investigate the role of microorganisms on “Erika” oil degradation, microbial mats from the Guérande salt marches were maintained in slurries containing the pollutant. From these slurries experiments, a low biodegradation rate of the “Erika” oil was detected indicating the degradation capacities of microbial mats. Biodiversity studies were conducted to further understand the biodegradation processes. Microbial mats from the Guérande salterns were maintained in microcosms to evaluate the impact of “Erika” oil on bacterial communities. Molecular analysis based on 16S rRNA and pufM encoding genes allowed fingerprinting of the bacterial and purple anoxygenic bacterial (PAB) communities respectively. These studies revealed bacterial diversity and communities changes showing the adaptation of microorganisms to the “Erika”