The community assembly patterns determined differences between the surface and the core microbial communities of Nongxiangxing Daqu

Abstract

High-throughput sequencing combined with a null model test was used to reveal the structural characteristics and assembly mechanisms of microbial communities in the surface of Daqu (SD) and the core of Daqu (CD) during fermentation. The results showed that microbial community differentiation occurs during Daqu fermentation, which resulted in differences between SD and CD microbial communities. In SD, Saccharomycetales and Mucorales were predominant in the fungal communities, and Lactobacillales were predominant in the bacterial communities. Meanwhile, in CD, Eurotiales and Bacillales were dominant in the fungal and bacterial communities. The co-occurrence network analysis revealed that microbial interaction is stronger in the CD than SD. Furthermore, the null model test showed that stochastic processes dominated SD and CD fungal community assembly throughout the fermentation period, but five processes contributed to the two community assemblies differed. During the later stage of fermentation, the SD bacterial community was mainly subjected to homogeneous selection by deterministic processes, while the CD bacterial community was probably more influenced by undominated. The study's findings indicate that the differences in community assembly patterns in different parts of the Daqu fermentation process were the main reason for community differentiation, which confers species diversity to Daqu.