In this study the bacterial diversity of thermophilic microbial mats (40 to 65°C) in three alkaline hot springs of the Baikal Rift Zone (BRZ) was determined through pyrosequencing of 16S rRNA gene...

The hydrochemical water composition and the mineralogical composition of microbial mats and bottom sediments were determined for the ephemeral saline soda lake Gudzhirganskoe (Barguzin Valley, Baikal Rift zone). Analysis of the 16S rRNA gene amplicons was applied to investigation of microbial diversity in several biotopes: brine (1 sample), sediments (3), and microbial mats (3). During sampling in October 2017, the lake was almost dry, with the residual brine (salinity 100 g/dm³) occurring occasionally, and microbial formations at two sampling points existing as dry crusts. A total of 38636 nucleotide sequences were analyzed and assigned to 193 OTUs. Bacteria predominated in all biotopes, while archaea constituted 0.013 to 4.5%. The biotopes exhibited differences in their taxonomic composition. Members of the Gammaproteobacteria (36.5%), Bacteroidetes (25.4%), and Alphaproteobacteria (18.3%) were predominant in the brine. The Gammaproteobacteria predominated (52%) in the dense dry crust (Gudzh 1-mat), while Cyanobacteria constituted only 3.4%. In the dry crust (Gudzh 2-mat), the Gammaproteobacteria also were the main component of the community (80%), primarily members of the genus Aliidiomarina (68%). In the bottom microbial mat below the residual brine, the community contained mainly Gammaproteobacteria (37.4%) and Cyanobacteria (27.8%). Firmicutes prevailed in the bottom sediments (30‒32%), while Actinobacteria (14.56%) and Deinococcus‒Thermus (15.4%) were subdominant at sampling point 1. These data made it possible to assess the present state of the lake and the taxonomic diversity of microbial communities in Lake Gudzhirganskoe biotopes.

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.

— Peptidase activity of alkaliphilic anaerobic proteolytic Proteinivorax bacteria, P. tanatarense Z-910T and P. hydrogeniformans Z-710T, isolated from the Tanatar system of hypersaline...

In the vast expanse of Baikal Siberia, indigenous nomadic animal groups have been conserved, grazing on pastures throughout the year. It is believed that the fecal microbiota of these diverse nomadic animal species is unique to each species and closely tied to their feeding environments. We conducted a pioneering comparative analysis of the taxonomic structure and the diversity of fecal microbiota in indigenous nomadic animals inhabiting Baikal Siberia. Our study encompassed 20 deer, 23 yaks, 24 camels, and 29 sheep, using high-throughput 16S rRNA gene profiling. In the fecal microbiota of these animals, we observed a predominant presence of the phyla Bacillota, Bacteroidota, and Verrucomicrobiota, collectively comprising over 88% of the microbial communities. Moreover, these proportions exhibited variations according to the host species. The unculturable Bacillota UCG-005 and UCG-010 are the key groups for all animals. However, at the genus level, distinctive compositions of fecal microbiota were discernible within each animal group. We identified a total of 37 dominant genera across the fecal samples from these four animal species. Principal component analysis (PCA) and cluster analysis demonstrated that the fecal microbiota composition clustered among individuals of the same animal species. Linear discriminant analysis effect size (LEfSe) indicated that camels exhibited higher abundances of the family Akkermansiaceae and the uncultured clostridial lineage UCG-010, while deer featured Lachnospiraceae; sheep had Ruminococcaceae; and yaks displayed Monoglobaceae, Bacteroidaceae, and methanogenic archaea from the family Methanobacteriaceae as distinctive marker taxa. Our studies showed that the studied nomadic animals feed mainly on plants belonging to the families Poaceae, Cyperaceae, Asteraceae, and Rosaceae. Our research indicated that the identity of the host species and, to a lesser degree, their diets and habitats, significantly shape the composition of fecal microbiota in these studied nomadic ruminant animals.

The peptidase activity of the alkaliphilic, aerobic, proteolytic bacteria Alkalicaulis satelles G-192T and Aliidiomarina sp. P-156 isolated from the system of hypersaline, alkaline Tanatar lakes (Altai Territory) was studied. Strains G-192 and P-156 710 were shown to hydrolyze para-nitroanilide substrates and exhibit the highest activity hydrolyzing of the aminopeptidase LpNa substrate. Analysis of partially purified peptidase preparations showed that the enzymes were most active and stablest in an alkaline pH range of 8.4–11. The peptidases of strains G-192 and P-156 were highly stable in NaCl up to 220 and 70 g/L respectively. The results of inhibitor analysis and the substrate specificity of the studied extracellular enzymes indicated their classification as metallopeptidases of the aminopeptidase type. The studied peptidases showed significant resistance to the surfactants Triton X-100 and SDS and the oxidizing agent H₂O₂. The isolated bacteria that produce peptidases can be used as a source of proteolytic enzymes in the development of new detergents.