Abstract:

Objective To explore the differences of intestinal flora between healthy Han and Tibetanpeople，so as to provide reference for race⁃microbiota hypothesis and the research on pathogenesis mechanism withmicrobiota as a study object. Methods A total of 128 fecal samples of healthy Han and Tibetan volunteers in thesame area were collected. 42 samples were screened by propensity score matching（PSM），including 14 Han and28 Tibetan samples. After high⁃throughput sequencing of the V3 plus V4 region in 16S rRNA gene of sample DNA，OTU table was generated and annotated. Based on the analysis of alpha and beta diversity，DESeq2 package andedgeR package of R language were used to analyze the difference in intestinal flora between Han and Tibetan；Net⁃work analysis was carried out by bnlean package，psych package and reshape2 package to screen the flora closelyrelated to ethnic factors，and the ethnic biomarkers of species at the genus level were identified by LEfSe analysis.Finally，the high⁃quality data were spliced and assembled by IDBA⁃UD software，the non⁃redundant gene set wasconstructed by CD⁃HIT software，and the metabolic pathway information and GO annotation results were obtainedby PICRUST analysis. The differences between the two groups were analyzed by STAMP software to compare thedifferences in metabolic pathways between the two groups. Results There were 199 different OTUs in intestinalflora between Han and Tibetan，proving that differences in intestinal flora existed between Han and Tibetan popula⁃tion. Ruminococcus，Anaeroplasma and Proteobacteria were significantly higher while Butyricum，Anaerostipes and Dialist were markedly lower in Tibetan intestinal flora than in Han flora. The flora closely related to ethnicfactors included Copri，Stercorea，and Haemophilus parainfluenzae. At the genus level，Pseudobutyricvibrio，Suc⁃cinicvibrio and Catenibaterium were the flora markers in Tibetan people，so were Dialster and Turibacter in Han.There were 10 different metabolic pathways. The significantly up⁃regulated pathways in the Tibetan group includedenzyme families，replication and repair，translation，nucleotide metabolism，metabolism of terpenoids andpolyketides. Conclusions This study partially verified the race⁃microbiota hypothesis. The influence of ethnic fac⁃tors should be considered in the study of flora and diseases.

Key words:

Han nationality, Tibetan nationality, intestinal flora, 16S rRNA