While the gut microbiome has been intensively investigated for more than twenty years already, its role in various disorders remains to be unraveled. At the same time, questions about what changes in the gut microbiota can be considered as normal or pathological and whether communities are able to recover after exposure to negative factors (diseases, medications, environmental factors) are still unclear. Here, we describe changes in the gut microbiota composition and the content of short-chain fatty acids in adult healthy volunteers (n = 15) over a 24 month-period. Intraindividual variability in gut microbial composition was 40%, whereas the short chain fatty acids profile remained relatively stable (2-year variability 20%, inter-individual 26%). The changes tend to accumulate over time. Nevertheless, both short-term and long-term changes in the gut microbiome composition were significantly smaller within individuals than interindividual differences (two-year interindividual variability was 75%). Seasonal changes in gut microbiota were found more often in autumn and spring involving the content of minor representatives (less than 1.5% of the community in average) in the phyla Actinobacteriota, Firmicutes and Proteobacteria.

Introduction. The concept of heterogeneity in obesity depending on the risk of developing cardiometabolic complications has garnered attention in recent decades, since not everyone with obesity goes on to develop metabolic dysfunction.The aim of the work is to study specific characteristics of colonic microbial communities in patients with different obesity phenotypes and in healthy individuals by employing metagenomics methods.Materials and methods. A total of 265 individuals (44 men and 221 women; mean age 47.1 ± 4.8 years) were enrolled in the study. They were further divided into clinical groups: Healthy normal-weight individuals (n = 129); patients with obesity (n = 136), including metabolically healthy obesity (n = 40) and metabolically unhealthy obesity (n = 55). Quantitative and qualitative assessment of the intestinal microbiome was based on metagenomic analysis. Fecal samples were used to isolate DNA and perform sequencing of the variable v3-v4 region of the 16S rRNA gene.Results. The study revealed statistically significant (p 0.05) differences between quantitative and qualitative variables in studied phylotypes of colonic microorganisms in healthy individuals without obesity and in patients with different obesity phenotypes.Discussion. Patients with obesity had higher levels of Bacteroidetes, Proteobacteria and lower levels of Actinobacteria, Firmicutes, TM7 (Saccharibacteria), Fusobacteria, and more frequently detected phyla Tenericutes, Planctomycetes and Lentisphaerae compared to healthy individuals. Metabolically healthy obese patients had more rarely detected phylum Lentisphaerae in their colonic microbiome, increased numbers of Firmicutes and reduced numbers of Bacteroidetes compared to metabolically unhealthy obese patients.Conclusion. The findings demonstrate alterations in the colonic microbiome in patients with different obesity phenotypes.

Crohn’s disease (CD) is a chronic relapsing inflammatory bowel disease of unknown etiology. Genetic predisposition and dysbiotic gut microbiota are important factors in the pathogenesis of CD. In this study, we analyzed the taxonomic composition of the gut microbiota and genotypes of 24 single nucleotide polymorphisms (SNP) associated with the risk of CD. The studied cohorts included 96 CD patients and 24 healthy volunteers from Russia. Statistically significant differences were found in the allele frequencies for 8 SNPs and taxonomic composition of the gut microbiota in CD patients compared with controls. In addition, two types of gut microbiota communities were identified in CD patients. The main distinguishing driver of bacterial families for the first community type are Bacteroidaceae and unclassified members of the Clostridiales order, and the second type is characterized by increased abundance of Streptococcaceae and Enterobacteriaceae. Differences in the allele frequencies of the rs9858542 (BSN), rs3816769 (STAT3), and rs1793004 (NELL1) were also found between groups of CD patients with different types of microbiota communities. These findings confirm the complex multifactorial nature of CD.

It is important to study the level of anthropogenic pollution of rivers in order to maintain the health of ecosystems and provide the sustainable development of society. Surface water pollution is mainly caused by urbanisation, agriculture and industrial discharges. Here, we present the results of a three-year study of the chemical composition and bacterial diversity of samples collected from three rivers of the Kuibyshev Reservoir. Statistically significant differences between chemical parameters and alpha diversity indices were found. In addition, a negative correlation was between the Shannon index and manganese content, and the Chao1 index with nitrite ions.

Пристеночная микробиота дивертикулов при воспалительных осложнениях дивертикулярной болезни (пилотное исследование)