Characterization of the microbial community compositions and diversities in the traditional fermented yak milk from different ecotopes on the Qinghai-Tibetan plateau

This study investigated the bacterial and fungal diversities and compositions in the traditional fermented yak milk from 5 major ecotopes of the Qinghai-Tibetan plateau. Totally 47 lactic acid bacteria species or subspecies were found in the traditional fermented yak milk, and the dominant bacterial species were Lactobacillus delbrueckii, Streptococcus salivarius, and S. thermophiles. Although differences in the relative abundances of bacteria were found among the samples from 5 ecotopes, there were no correlations between the dominant lactic acid bacteria species and the pH of traditional fermented yak milk or altitude, longitude, and latitude of sampling sites. There were 9 yeast species and Saccharomyces cerevisiae, Pichia kudriavzevii and Debaryomyces hansenii were the dominant fungal species. Among the 5 ecotopes, samples from the ecotope located in the western region of the plateau with the harshest environment (altitude 4591–4977 m) had the lowest relative abundance of L. delbrueckii but the highest S. salivarius and S. thermophiles. In brief, the present study provides important information on an overview of the microbial resources in the traditional fermented yak milk from the Qinghai-Tibetan plateau, and the ecological regions had a remarkable influence on the microbial compositions in the traditional fermented yak milk.