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”.