Microbial Community of Umkhei Thermal Lake (Baikal Rift Zone) in the Groundwater Discharge Zone
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obial Community of Umkhei Thermal Lake (Baikal Rift Zone) in the Groundwater Discharge Zone E. V. Lavrentyevaa, b, *, T. G. Banzaraktsaevaa, A. A. Radnaguruevaa, S. P. Buryukhaeva, V. B. Dambaeva, O. A. Baturinac, L. P. Kozyrevaa, and D. D. Barkhutovaa aInstitute
of General and Experimental Biology, Siberian Branch, Russian Academy of Sciences, Ulan-Ude, 670047 Russia b Buryat State University, Ulan-Ude, 670000 Russia c Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia *e-mail: [email protected] Received February 26, 2019; revised May 6, 2019; accepted May 7, 2019
Abstract—The diversity and functional activity of the microbial community of the bottom sediments and water of the thermal alkaline Umkhei Lake (Baikal Rift Zone), which was formed as a result of groundwater discharge, has been studied. The lake water is shown to be thermal hydrocarbonate–sulphate–sodium water of the Kuldur type. Lake sediments are characterized by higher temperatures and greater saturation with microelements. A comparative analysis of the species abundance of the microbial community of water and bottom sediments shows high indices of diversity in all layers of sediments, while the diversity in water is low. An analysis of taxonomic diversity reveals the predominance of the members of Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Chloroflexi phyla in the community of water and bottom sediments. The presence of bacteria with various metabolic pathways of substance and energy transformation in both production and destruction processes is determined. The sequences belonging to the genus Hydrogenophaga (class β-Proteobacteria, phylum Proteobacteria), which is an indicator of the deep geochemical processes of hydrogen production, are found in the bottom layers of sediments. The rates of microbial processes of photosynthesis, dark assimilation of CO2, sulfate reduction, and methanogenesis are determined to characterize the functional activity. The main part of the organic-matter production in water is found to be formed as a result of the activity of chemolithoautotrophic prokaryotes. In the microbial community, the producers synthesize organic matter using volcanogenic carbon dioxide enriched in the heavy isotope (δ13C). An analysis of the rates of terminal processes indicates that sulfate reduction is the main process. Keywords: groundwater discharge zone, thermal lake, taxonomic diversity of the microbial community, functional activity, Baikal Rift Zone DOI: 10.1134/S1995425519060088
INTRODUCTION Recently, research devoted to the study of the functional diversity of microbial communities in the upper layers of the underground sphere of alkaline mineral springs has been carried out (Blazejak et al., 2010; Namsaraev et al., 2011; Breuker et al., 2011; Brazelton et al., 2012; Tiago and Verissimo, 2013; Schrenk et al., 2013; Teske et al., 2013; Slobodkin and Slobodkina, 2014; Kadnikov et al., 2017). The transit zones of mixing of groundwater and surface
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