Gut microbiomes of tribal communities in India vary with dairy and grain consumption.

Highly diverse gut microbiomes of non-industrialized populations share similarities with ancestral states of symbiosis and are linked to low rates of chronic inflammatory diseases. Yet there is still limited understanding of the diverse array of non-industrialized gut microbiomes throughout the world, including among the tribal populations of India. In this study, we surveyed dietary and fecal microbiome variation among 76 adults from eight tribal communities in four biogeographic regions of India, including Warli on the western coast, Gond and Madia in the northeast Deccan Plateau, Kabui (or Rongmei Naga) in the northeast hills of the Himalayas, and Balti, Boto, Brokpa, and Purigpa in the northwest Trans-Himalayas. Metagenomic and 16S sequencing of fecal samples identified Segatella, Agathobacter, and Faecalibacterium as core members of the gut microbiome of all populations, with Segatella copri (formerly Prevotella copri) dominant at mean 25%-47% relative abundance. Four Trans-Himalayan populations with diets uniquely defined by dairy and diverse cereals had elevated gut alpha diversity and distinct beta diversity, driven by prevalent and abundant Bifidobacterium as well as taxa shared with the ruminant microbiome. Strains of B. adolescentis present in the dairy-consuming populations were genetically distinct from industrialized strains around the world and encoded CAZymes consistent with selection by dairy and grain consumption. The gut microbiomes of a minority of subjects shared taxonomic and functional features with a previously described sample of Californians, suggesting that the pressures posed by globalization could be impacting the microbiomes of tribal populations. These results highlight the nutritional and microbiological contribution of dairy livestock in shaping gut communities and emphasize the large effect that lifestyle can have on the diversity and function of non-industrialized gut microbiomes.