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Identification of patterns of formation of bacterial communities of the rhizosphere and rhizoplane of potato (Solanum tuberosum L.), the most important agricultural crop, is necessary for the introduction and maintenance of sustainable organic farming. The purpose of this work was the study of the biodiversity of the bacterial microbiota of the rhizosphere and rhizoplane of Early Zhukovsky potato, cultivated on gray forest soils. Comparative analysis based on sequencing of the 16S R RNA gene showed a significant difference in the representation of different groups of bacteria in these potato root compartments. Thus, the proportions of the dominant bacteria in the rhizosphere and rhizoplane of the Proteobacteria phylum reach 47.66% ± 7.22 % and 86.35 % ± 0.53%, respectively (P < 0.05). In contrast, the representation of phylum Bacteroidetes and Firmicutes in the rhizosphere is significantly higher and reaches 41.45 % ± 10.42% and 6.49 % ± 3.23%, respectively, compared to the rhizoplane (7.84 % ± 1.24 % and 0.43 % ± 0.48 %, (P < 0.05). At the same time, Actinobacteria phylum bacteria are present in both compartments in approximately equal amounts (4.40 % ± 1.81% in the rhizosphere and 5.37 % ± 1.42% in the rhizoplane). Thus, it was found that potato forms different bacterial communities in the rhizosphere and rhizoplane in quantitative proportions, which is probably determined by the functional role of these microorganisms in the plant physiology.

The paper analyzes fungi of the genus Fusarium isolated from plants and tubers of different potato cultivars grown on the territory of Tatarstan. It was established that the majority of the strains belonged to the Fusarium oxysporum species complex. Isolates obtained from the root necks of wilting potato plants and conditionally healthy tubers are, to varying degrees, capable of causing dry rot of tubers during artificial inoculation. Also, the virulence of the strains does not correlate with extracellular proteolytic activity. It was shown that the tubers of the Zhukovskij rannij cultivar are most sensitive to fusaria infections, in contrast to the Red Scarlet and Reggi cultivars.

Intestinal microbes play a key role in the energy metabolism of broiler chickens, participate in the development of the gastrointestinal tract, including the regulation of intestinal epithelial proliferation, vitamin synthesis and ion absorption, fermentation of carbohydrates and proteins, biotransformation of bile acids, protection from pathogens and modulation of the immune system. Metagenomic analysis of the gastrointestinal microbiota allows to find approaches to improve the growth and productivity of chickens by introducing a diet based on beneficial bacterial strains or their secondary metabolites. In this paper, we studied the effect of the total fraction of Bacillus subtilis GM5 lipopeptides on the growth parameters and formation of bacterial communities in the caecum of cross Cobb 500 broiler chickens. It was found that the addition of bacillary lipopeptides to the feed resulted in an increase in chicken weight by 12.7% and a decrease in feed conversion by 6.36% compared to the control (P < 0.05). It was also shown that the introduction of a feed additive in the form of a lipopeptide fraction modulates the structure of the bacterial microbiota of the caecum of chickens. Thus, the proportion of classes Bacteroidia, Negativicutes, Betaproteobacteria, Epsilonproteobacteria, Deltaproteobacteria, Synergistia in the caecal microbiota of chickens of the experimental group increases, and the proportion of Clostridia, Methanobacteria decreases in comparison with the control.

The objective of the study was to determine the effect of adding protease obtained from the Bacillus pumilus 3-19 strain to the diet of Hubboard broiler chickens on the growth indicators of poultry and the composition of the cecum microbiota of broiler chickens. As a result of metagenomic analysis of 16S rRNA genes in the contents of the cecum of chickens, it was shown that the control and experimental groups formed two separate clusters, which indicates differences in microbial communities in these two groups. Analysis of alpha diversity showed an increase in species richness in the group of chickens that received protease as a feed additive. On day 35, both groups were dominated by bacterium of Firmicutes (21.13 — 49.01%) and Bacteroidetes (37.68 — 67.72%) groups. It was shown that in the group of chickens receiving protease as a feed additive, the average daily gain in live weight was higher than in the control group by 0.5 kg (P < 0.05). The introduction of protease resulted in an increased F/B ratio, which was positively correlated with chicken body weight. Thus, the addition of B. pumilus 3-19 protease to broiler feed leads to improved feed intake and digestibility, which is of great importance for reducing the cost of the final product. The use of protease regulates the cecum microbiota of broiler chickens and increases microbial diversity on 35 day of chicken growth.

In this paper, the probiotic properties of Bacillus subtilis GM2 and GM5 strains were studied. It is shown that the use of probiotic additives based on the spores of these bacteria leads to an increase in the live weight gain of broiler chickens by 4.16% and 10.76% relative to the control. Metagenomic analysis showed that representatives of the phylum Firmicutes (54.55%) and Bacteroidetes (30.45%), mainly represented by the families Ruminococcacea and Bacteroidaceae, predominate in the caecal microbiota of broiler chickens on day 42. It was found that a probiotic based on the B. subtilis GM5 strain leads to an increase in the proportion of Firmicutes in caecum by 27% and a decrease in Bacteroidetes by 19%. There was also a significant decrease in the number of representatives of opportunistic pathogenic bacteria of the Enterobacteriaceae family relative to the control group.