Endocrine Abstracts

Background: Network analysis of species abundance across different individuals suggested that the overall structure of the human gut microbiota in each individual conforms to discrete and distinct patterns defined by interactions within community members. This hypothesis was investigated using a dataset of metagenomic sequences from American, European and Japanese individuals. Multidimensional cluster analysis and principal component analysis revealed that all individual samples formed three robust clusters, which have been designated as ‘enterotypes’.

Aims: To determine the enterotypes of gut microbiome and their metabolic activity in Russian population.

Materials and methods: To determine the phylogenetic and functional basis of the enterotypes, we investigated in detail their differences in composition at the phylum, genus, gene and pathway level as well as correlations in abundance of co-occurring genera. We analyzed gut microbiota in 92 patients with various glucose tolerance: normal glucose tolerance (n=48), prediabetes (n=24) and type 2 diabetes (T2D) (n=20). Metagenomic analysis was performed using 16SrRNA sequencing.

Results: The dominant bacteria in total samples composition were two main phyla: Bacteroidetes (12.7±9.86%) and Firmicutes (57.09±13.6%). Taxonomic analysis of the sample revealed two clusters with average silhouette value 0.22. After the clustering into enterotypes the Prevotella, Oscillospira, Flavobacterium, Sphingobacterium, Parabacteroides abundance turned to be higher in the first cluster, and the Ruminococcus, Peptoniphilus, Thiothrix, Legionella in the second cluster (P<0.004). There were no sex and age differences in the clusters, but the T2D prevalence was higher (P=0.016) in the second cluster. The relative abundances of the different species making up the samples’ richness are defined as ‘evenness’. The Shannon-diversity index relates both, OTU richness and evenness. We found that the microbial diversity (alpha diversity) (P=8.089e-05) and the percentage of pathways for the synthesis of vitamins B9, B2, B6, K were significantly less, but the percentage of pathways for the synthesis of vitamin B12 significantly higher in the second cluster. The second cluster had a smaller representation of enzymes that convert butyryl-CoA into butyrate.

Conclusions: Despite the absence of high confidence taxonomic clustering, we found two enterotypes in the gut microbiota of Russian population that vary in species, functional composition, T2D prevalence and are sex and age independent.