Bacterial Diversity of the Soil of the Polar Tundra of Russia

— This review summarizes the results of the study of bacterial communities of seasonally thawed soil horizons in the polar tundra of Russia. It has been shown that the representatives of different physiological groups of microorganisms developing in the soils of this extremely cold habitat are involved in the global biological cycle of carbon. Light has been thrown upon the role of microorganisms in the formation of volatile organic compounds including gases (methane, hydrogen) during anaerobic decomposition of soil organic matter and their uptake by aerobic bacteria, which are a kind of bacterial filter for volatile organic compounds on their way to the atmosphere. It has been shown that the bacteria of Soehngen cycle developing in the soil of the polar tundra of Russia at low temperatures control the flow of methane, one of the greenhouse gases formed by the anaerobic microbial community at the methanogenic step, into the atmosphere. The community also includes methylotrophic bacteria using oxidized and substituted methane derivatives as carbon and energy sources, which are a biofilter for volatile C 1 compounds on their way to the atmosphere. The pure cultures of psychrophilic and psychroactive representatives of hydrogen, methanotrophic, methylotrophic, heterotrophic bacteria of the microbial community of tundra soil have been described. It has been shown that the microbial community is characterized by high species diversity. In general, the bacteria of the seasonally thawed horizon of tundra soil are adapted to exist in extreme habitats: cold tundra ecosystems.