Abstract: Ethnicity is considered as one of the major driving forces to shape the human gut microbiota, but how the gut microbiota evolves in population with disparate ethnic backgrounds since infants are born remains still unclear. Thus, this study aimed to understand the impact of ethnicity on infants. We investigated the fecal microbiota of healthy infants (3–6 months old, with breast feeding) from the Chinese Han and Tibetan ethnic groups (n = 10 for each group). By using high-throughput 16S rRNA gene sequencing analyses, we found some differences in fecal microbiota composition between the two groups. At the phylum level, the Han infants harbored higher relative abundance of Actinobacteria, whereas Firmicutes was more predominant in the Tibetans. A significant difference at the phylum level existed in Firmicutes (P < 0.05) between the two groups. Bifidobacterium and Escherichia-Shigella were the first and second major genera in both groups, respectively. There was a clear separation between the groups by principal coordinates analysis (PCoA) based on unweighted and weighted UniFrac distance. Moreover, partial least squares-discriminant analysis (PLS-DA) showed that the infant gut microbiome was segregated according to ethnicity. Taken together, our findings suggest that the gut microbiota could be differentiated between infants from distinct ethnic origins, and this expanded our knowledge of the co-evolution of human hosts and their symbiotic gut microbiota.

Key words: infant, gut microbiota, ethnicity, co-evolution