Formation and functioning of microbial mats in mineral spring Hoito-Gol (Eastern Sayan)

The bacterial species composition involved in the production and destruction of organic matter of microbial mats in the spring Hoito-Gol, located in the Eastern Sayan mountain range, was studied. The mineral spring water relates to hydrocarbonate-sodium type, with the hydrogen sulfide content to 7 mg/l. Hydrogen sulfide stands out from the depths with volcanic fluids and forms in microbial sulfate reduction process in sediments. Microbial mats were formed by cyanobacteria Phormidium sp. and colorless sulfur bacteria Thiothrix sp. High number of autotrophic and heterotrophic microorganisms (up to 108 cells/ml) was detected. A feature of the microbial mats functioning of spring Hojto Gol was dominance and diversity of sulfur cycle bacteria. Important role in the sulfur cycle bacteria in spring Hojto Gol confirmed by high numbers of sulfate-reducing bacteria and sulfur-oxidizing bacteria, and intensive processes of sulfate reduction and anoxic photosynthesis. We obtained pure cultures of purple non-sulfur bacteria ( Rhodopseudomonas palustris, Rhodobacter capsulatus, Rhodomicrobium vannielii ), filamentous anoxigenic bacteria ( Oscillochloris trichoides ), green sulfur bacteria ( Chlorobium limicola ), sulfur-oxidizing bacteria ( Thiobacillus thioparus ), sulfate-reducing bacteria ( Desulfovibrio alcoholivorans ) and showed their activity in sulfur cycle in the microbial mats.