Microbial Communities Associated with Bentic Invertebrates of Lake Baikal.

The first results of a study into the microbiomes of benthic invertebrates found in sites with seeps (containing methane, oil, or a combination of methane and mud) and an underwater low-temperature vent of Lake Baikal are presented. Microorganisms were detected in the intestine of an oligochaete from the cold methane seep using microscopy. Analysis of 16S rRNA gene libraries revealed that the highest diversity of microorganisms was found in the nematode microbiomes where the members of 11 phyla were identified. Some of the detected prokaryotes are methanogens, nitrifiers, and nitrogen fixators, while some are involved in the sulfur cycle. Methanotrophs were detected in the microbiomes of oligochaetes and chironomids. The microbiomes of nematodes, chironomids, and bathynellids are composed of members of the Bacteroidetes and Firmicutes phyla, which are related to the symbiotic bacteria found in insects and animals from other ecotopes. Microorganisms typically found in the water and sediments of Lake Baikal were also detected in the invertebrates microbiomes.