The analysis of the literature on the microbiome composition and metabolic properties of kefir available at the RSCI and Web of Science was carried out. Kefir has been used by humans for centuries. It is a useful product of mixed lactic and alcoholic fermentation, produced using evolutionally established associative cultures, collected in an aggregated state termed kefir grains. General characterization of kefir grains from the territorial zones of different continents (Russia, Europe, Asia, and America) is provided. The methods for differentiation and identification of individual species are described, as well as their interactions within the community. The diversity of microbial composition of kefir grains depending on local cultivation conditions and storage processes is shown. The microorganisms present in kefir have a number of properties that determine their metabolism, interaction in the community, beneficial effects on human health and immune system, which is important for the prevention and control of bacterial and viral infections, especially during the COVID-19 pandemic.

Currently, a number of structurally and functionally different temperature-sensitive elements such as RNA thermometers which control a variety of biological processes in bacteria, including virulence, are known. Based on computer and thermodynamic analysis of completely sequenced genomes of 25 isolates, the algorithm and criteria for the search of potential RNA thermometers were developed. It will make it possible to carry out the search for potential riboswitches in the genome of other socially important pathogens. For , apart from the known 4U RNA thermometer, four hairpin-loop structures were identified which may probably act as additional RNA thermometers. They satisfy the necessary and sufficient conditions for formation of RNA thermometers and are highly conservative uncanonical structures, since these highly conservative structures were found in the genome of all 25 isolates of . The hairpins forming a cruciform structure in the supercoiled pUC8 DNA were visualized by atomic force microscopy.

The optimal conditions for C3 oxidative biotransformation of 1.0 g/L pentacyclic triterpenoids oleanolic (OA) and glycyrrhetinic (GA) acids were determined using the resting cells of IEGM 1360 from the Regional Specialised Collection of Alkanotrophic Microorganisms. Resting cell suspensions (OD 2.6, pH 8.0, and OD 2.2, pH 6.0) showed the highest catalytic activity against OA and GA, resulting in the formation of 61 and 100% of their 3-oxo derivatives, respectively. Using phase contrast, atomic force, and confocal laser scanning microscopy, an adaptive response of rhodococci to the effects of OA and GA was revealed. , the apoptotic activity of 3-oxo-OA and antioxidant activity of 3-oxo-GA have been assumed. In vitro, a pronounced antibacterial activity of 3-oxo-OA against , , , and was shown. The absence of toxic effects of the above triterpenoids and their 3-oxo derivatives on aquatic objects and plants was demonstrated and in vitro, respectively.