Pyrosequencing analysis of the school children salivary microbiome from Han, Tibetan, and Hui ethnics in the Qinghai–Tibetan Plateau

Oral microbiota is affected by multiple factors, including dietary, drinking, ethnicity, and smoking, while little is known about how the oral microbiome varies across healthy school children with different ethnic backgrounds living in the same geographic regions. Meanwhile the relationship between oral microbiota and gut microbiota also need further research, due to previous studies mainly focusing on a single body habitat. Here, we collected saliva and gut samples from 60 school children covering the Tibetan, Han and Hui ethnicities and living in the Qinghai–Tibetan Plateau. The microbial composition of saliva and gut was sequenced by Illumina MiSeq high-throughput sequencing. Bacteroidetes (41.19%) and Proteobacteria (24.83%) was the dominant phyla in the oral. 5 genera of oral microbiota showed significant differences in relative abundance. The alpha diversity (Shannon diversity) of saliva in Tibetan group was lowest than that in the Hui and Han groups, whereas the beta diversity of saliva was similar among the three groups. Based on the sample sites, saliva had higher alpha diversity than that in the gut among the three groups, but there was no association between the alpha diversity of oral and gut microbiota. In addition, Principal Coordinate Analysis (PCoA) indicated that oral microbiota was completed separated from gut microbiota. The consumption of seafood, poultry meat, sweets, and vegetables was correlated with multiple oral microbiota. Some oral bacterial genera were also associated with gut microbial genera. Our results suggested that the diversity and composition of salivary microbiome had slight differences among the different ethnic groups. Meanwhile, dietary probably affected the salivary microbiome composition and the salivary microbiota might have an association with the gut microbiota.