Diversity and Metabolism of Microbial Communities in a Hypersaline Lake along a Geochemical Gradient

SIMPLE SUMMARY: In the south of western Siberia (Russia), there are many unique and unexplored lakes. This work focused on Lake Solenoe, a component of a poorly studied lake system in the south of western Siberia. The diversity of microorganisms of Lake Solenoe was evaluated in the floating community and in the bottom sediments. The aim was to assess the metabolic potential of this lake ecosystem and to describe the identified relations between the mineral and living components. This is the first detailed study on the microbial diversity, its metabolic potential, and their relations with a series of geochemical parameters in the lake ecosystem of Novosibirsk Oblast. ABSTRACT: In the south of western Siberia (Russia), there are many unique and unexplored soda, saline, and freshwater lakes. In this study, the results are presented on microbial diversity, its metabolic potential, and their relation with a set of geochemical parameters for a hypersaline lake ecosystem in the Novosibirsk region (Oblast). The metagenomic approach used in this work allowed us to determine the composition and structure of a floating microbial community, the upper layer of silt, and the strata of bottom sediments in a natural saline lake via two bioinformatic approaches, whose results are in good agreement with each other. In the floating microbial community and in the upper layers of the bottom sediment, bacteria of the Proteobacteria (Gammaproteobacteria), Cyanobacteria, and Bacteroidetes phyla were found to predominate. The lower layers were dominated by Proteobacteria (mainly Deltaproteobacteria), Gemmatimonadetes, Firmicutes, and Archaea. Metabolic pathways were reconstructed to investigate the metabolic potential of the microbial communities and other hypothetical roles of the microbial communities in the biogeochemical cycle. Relations between different taxa of microorganisms were identified, as was their potential role in biogeochemical transformations of C, N, and S in a comparative structural analysis that included various ecological niches.