Factors controlling the activity of the microbial community of the alkaline Lake Beloe (Transbaikal Region)

In this work, the main environmental factors determining the functioning of the microbial community of the alkaline low-mineralized Lake Beloe during the annual cycle were studied. High numbers of phototrophic and heterotrophic microorganisms (up to 10⁷ cells/mL) and high rates of bacterial processes of organic matter (OM) production and destruction were observed. The highest rate of dark CO₂ assimilation (up to 0.43 mg C dm⁻³ day⁻¹), as well as the peak intensities of the terminal processes of sulfate reduction and methanogenesis (up to 1.81 mg S dm⁻³ day⁻¹ and 0.96 μL CH⁴ dm⁻³ day⁻¹, respectively), detected at the end of summer, were comparable to the rates of these processes detected in the bottom sediments of most soda lakes of the Transbaikal Region. Principal Component Analysis (PCA) allowed us to estimate the effect of environmental factors on the functioning of the microbial community of the alkaline Lake Beloe. Four main components, explaining 98% of variations, were detected. The first one (PC1) explained 63.5% of the seasonal variations and represented the temperature factor consisting of the temperatures of air, water, and bottom sediments. Water temperature and pH were the main contributors to the second component (PC2) and determine 26.2% of the seasonal variations. The PC3 (silt temperature and the concentration of organic matter) and PC4 (salt concentration) components were less important and explained only 6.5 and 2.2% of the variations, respectively.     

Alkalisalibacterium limincola gen. nov., sp. nov., an Alkaliphilic Bacterium Isolated from an Alkaline,Saline Lake of Buryatia in Russia

Microbiology - A gram-stain-negative, aerobic, rod-shaped and motile bacterium, designated Alg18-2.2T, was isolated from a bottom sediment of the highly alkaline-saline lake in Buryatia, Russia....     

Structure of Microbial Communities of the Sediments of Alkaline Transbaikalia Lakes with Different Salinity

The goal of the work was to reveal the differences in the structure of microbial communities of Transbaikalia alkaline lakes stemming from the differences in their salinity and hydrochemical parameters. The lakes studied were Verkhnee Beloe (Buryat Republic, Russia), as well as Khilganta, Gorbunka, and Borzinskoe (Transbaikal krai, Russia) with salinity from 12.3 to 430 g/L, which differed in the mineral composition of the sediments and hydrochemical parameters. Lake sediments were found to contain 47 prokaryotic phyla (42 bacterial and 5 archaeal ones). The phyla Proteobacteria, Euryarchaeota, Bacteroides, Chloroflexi, Actinobacteria, and Firmicutes were predominant, comprising over 95% of the classified sequences. Comparative abundance of archaea increased with salinity from below 1% in Lake Verkhnee Beloe to 35% in Lake Borzinskoe. The most numerous bacterial OTUs belonged to gammaproteobacteria of the genus Halomonas (up to 15% of the number of classified sequences). The most numerous archaeal OTUs were identified at the genus level as members of the genera Halorubrum and Halohasta belonging to the family Halorubraceae, which comprises extremely halophilic Euryarchaeota.