Substrate Specificity of Methanogenic Communities from Lake Baikal Bottom Sediments Associated with Hydrocarbon Gas Discharge

Methane production by microbial communities from Lake Baikal bottom sediments with different chemical composition of pore water was studied. Methane production was more active in the media supplemented with H2: CO2 and H2 + CH3COONa, rather than on media with acetate as the sole source of carbon and energy. Addition of methanol stimulated methane production only in the case of microbial communities from upper silts. Ability of the communities to produce methane correlated reliably with the concentrations of the NO3–, SO42−, Cl–, and CH3COO– ions in the pore water of the relevant sediments. Cultivation of communities from the mud volcano sediments resulted in development of methanogenic archaea of the family Methanocellaсеае in the media supplemented with H2: CO2 and H2 + CH3COONa, while methanogenic archaea in the communities cultivated without additional substrates belonged to the genera Methanoregula, Methanobacterium, and Methanosaeta.