The Buryatian horse is an ancient breed and, as an indigenous breed, they have unique adaptive abilities to use scarce pastures, graze in winter, and survive in harsh conditions with minimal human care. In this study, fecal microbiota of Buryatian horses grazing in the warm and cold seasons were investigated using NGS technology on the Illumina MiSeq platform. We hypothesized that the composition of microbial communities in the feces of horses maintained on pasture would change in the different seasons, depending on the grass availability and different plant diets. We conducted microhistological fecal studies of horse diet composition on steppe pasture. The alpha diversity analysis showed horses had a more abundant and diverse gut microbiota in summer. There were significant effects on the beta diversity of microbial families, which were clustered by the warm and cold season in a principal coordinate analysis (PCoA), with 45% of the variation explained by two principal coordinates. This clustering by season was further confirmed by the significant differences observed in the relative abundances of microbial families and genera. The obtained results can serve as an experimental substantiation for further study of the impact of pasture grasses, which have a pharmacological effect, on the diversity of the gut microbiome and horse health.

Bacterioplankton community taxonomic composition of four large freshwater lakes of the Yeravninskaya depression (Bolshoye Yeravnoye, Gunda, Isinga, and Sosnovoye) which have great fishery significance for the region has been studied. The microbial community consists in the main of bacterial phyla Gammaproteobacteria (22-74%), Actinobacteria (4-35%), Firmicutes (1.17-34.6%), Bacteroidetes (0.3-7%), Cyanobacteria (0.9-6.5%) and Planctomycetes (1.5-10.5%). Total dissolved solids and sulphates accounted for 57% of the variation in the microbial community distribution. At the genus level, Acinetobacter dominated (average 21.4-25.2%). Pseudomonas, Exiguobacterium, and Massilia were also widespread. Their predominance may indicate a possible change in the structure of the community caused by natural and anthropogenic factors. In lakes Isinga and Gunda, a large number of bacteria of the genus Klebsiella was observed, Staphylococcus and Streptococcus were detected. These features indicate insufficient water quality as a result of anthropogenic impact.

The taxonomic composition of microbial communities of eight large fresh lakes of Buryatia was studied. These lakes are Baikal, Kotokel, Gusinoye, Shchuchye and lakes of the Eravno-Kharginskaya group (Isinga, Gunda, Sosnovoe, Bolshoe Eravnoe). They have water management, fishery and recreational significance. At the phylum level, the microbial communities of the studied lakes were similar but the phyla abundance was varied. They consisted of typical freshwater taxa Pseudomonadota, Actinobacteriota, Bacteroidota, Cyanobacteriota, Firmicutes, Planctomycetes and Verrucomicrobia. At the genus level, Acinetobacter and Pseudomonas were numerous in all lakes. Other dominant taxa were Flavobacterium, hgcI clade in the fresh lakes of the Baikal region and Exiguobacterium, Klebsiella in the Eravno-Kharginskaya lakes. The feature of Eravno-Kharginskie lakes was the abundance of the genera Exiguobacterium and Klebsiella, as well as the detection of sanitary-significant bacteria. These facts may indicate pollution as a result of pressing various factors, including anthropogenic ones.