[Microbial communities of the discharge zone of oil- and gas-bearing fluids in low-mineral Lake Baikal].

At the site of natural ingress of oil microbial diversity in the Central Baikal bottom sediments differing in the chemical composition of pore waters was studied by molecular biological techniques. The sediments saturated with oil and methane were found to contain members of 10 bacterial and 2 archaeal phyla. The oxidized sediment layer contained methanotrophic bacteria belonging to the Alphaproteobacteria, which had a specific structure of the pmoA gene and clustered together with uncultured methanotrophs from cold ecosystems. The upper sediment layer contained also oil-oxidizing bacteria and the alkB genes most colsely related to those of Rhodococcus. The microbial community of reduced sediments exhibited lower diversity and was represented mostly by the organisms involved in hydrocarbon biodegradation.