Taxonomic diversity of fecal microbiota associated with different metabolic phenotypes in residents of Arkhangelsk, Northwestern Russia

The study aimed to assess the taxonomic diversity and composition of gut microbiota in Arkhangelsk residents, Northwestern Russia, with varying metabolic statuses. A population-based cross-sectional "Know Your Heart" study (2015-2017, participants aged 35–69 years) included a health examination and gut microbiota analysis (n = 685). Participants were divided into four metabolic phenotypes: metabolically healthy non-obese (MHN), metabolically unhealthy non-obese (MUN), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). Analyses were performed using RStudio software (v.4.2.0) with the vegan and phyloseq packages (v.1.42.0) for microbiota analysis. The sample was distributed across phenotypes as follows: MHN (47.6%), MUN (22.1%), MHO (10.4%), and MUO (19.9%). Beta-diversity analysis revealed significant differences in overall microbiome composition between MUO and MHN participants, while alpha-diversity did not differ significantly across phenotypes. The MHN group was characterized by a higher abundance of beneficial commensals such as Christensenellaceae R-7 group, Ruminococcaceae UCG-005, and Eubacterium xylanophilum group, which are taxa previously associated with metabolic health and longevity. In contrast, the MUO group showed an increased abundance of Streptococcus salivarius and Negativibacillus, taxa linked to gut dysbiosis and metabolic disorders. Blautia spp. emerged as a major hub in the microbiota of obese participants, consistent with its reported association with visceral fat. In conclusion, microbial composition was similar in obese participants despite metabolic dysfunction, whereas unidirectional taxonomic shifts were observed in those with metabolic dysfunction alone. The differences in the predominance of microbial taxa across metabolic phenotypes suggest that these taxa have a role in the development of metabolic disorders and obesity.