Bacteriobenthos of sapropel hydrogen sulfide lake Shungaldan (Mari Chodra National Park Republic of Mari El)

The first results of the study of the bacterial community in sapropel bottom sediments of hydrogen sulfide Lake Shungaldan are presented. The quantitative and dimensional-morphological structure was determined, the taxonomic composition of bacteriobenthos was established. The total abundance of bacteria was 11.41×109 cells mL-1 of silt, the biomass was 1.15 μg mL-1of silt. A feature of the size-morphological structure is a significant predominance of bacteria with linear sizes of 1.0-2.0 μm (85% of the total abundance) and the dominance of bacillus-shaped cells (83%). As part of the bacteriobenthos community, 31 taxa, including class Cyanobacteria, family Enterobacteriaceae, 20 taxa of genus and 9 taxa of species ranks. The basis of the community consists of bacteria that carry out the sulfur cycle, and microorganisms with a fermentation type of metabolism. The dominant are sulfate-reducing bacteria of the genera Desulfobacterium, Desulfotomaculum, butyric bacteria of the genus Clostridium, Butyrivibrio, anaerobic fermenter-dissipotrof of the genus Spirochaeta, facultative anaerobe Aeromonas. The bacteria of the iron cycle occupy secondary positions. In the sapropel of the lake, one of the main strategies for the destruction of organic matter are implemented - dissimilation sulfate reduction and anaerobic fermentation.