Monitoring bacterial communities adaptation to mercury contamination in estuarine sediments maintained in slurries

Adour sediments were incubated in slurries and polluted with inorganic mercury (HgCl,) to follow the adaptation of microbial communities to mercury. Mercury methylation was observed only in slurries maintained under anoxic conditions. Temporal variation of microbial community structure was identified using molecular approaches. The T-RFLP method based on the 16S ribosomal RNA encoding gene analysis demonstrated that microbial community structure was strongly dependent of mercury methylation potential. The analysis based on the functional mer genes involved in mercury resistance mechanisms revealed the presence of well adapted bacterial populations in Adour sediments. Furthermore significant modifications of the distribution of mer genes during incubation time were observed indicating that mercury addition influenced also the resistant populations.