Comparative analysis of the microbial community composition between Tibetan kefir grains and milks

In this study, we have investigated the bacterial and fungal community compositions in five Tibetan kefir grains (grain group) and five related kefir milks (milk group) via a combination of high-throughput sequencing technology and comparative bioinformatics analyses. According to the high-throughput sequencing technology, a total of 2,099,928 and 1,978,404 high-quality valid sequences were obtained from the bacterial and fungal communities of ten analyzed samples, respectively. Sequences were analyzed from family to species level for microbial community composition analysis. At the species level, a total of thirteen bacterial species and forty-six fungal species were detected, among which eight bacterial species and six fungal species with the relative abundances higher than 0.05% in at least one sample were further applied for the comparative bioinformatics analyses in the microbial community composition between the grain group (TKG1-5) and milk group (TK1-5), revealing that the fungal community compositions of grain and milk groups were similar; however, considerable differences were found in the bacterial community composition between the grain and milk groups. Both differences and similarities in the microbial community composition between the grain and milk groups were clearly revealed.