Abstract: The changes in the microbial niche and community assembly of fermented grains for Nongxiangxing baijiu during fermentation by Saccharomyces cerevisiae were analyzed to explore the mechanism for the influence of inoculation with S. cerevisiae on the microbial succession of fermented grains. In this study, a strain of S. cerevisiae isolated from fermented grains for Nongxiangxing baijiu was inoculated into distilled grains for fermentation experiments, and the microbial community structures of fermented grains with (experimental) and without (control) inoculation with S. cerevisiae were studied by high-throughput sequencing technology, and the niche changes of the control and experimental groups were studied by statistical analysis, and the mechanism of microbial community assembly was analyzed by the zero model. The results showed that compared with the control group, the diversity, species composition and niche width of microbial communities in the experimental group decreased, and the relative content of specialized species groups increased. In the co-occurrence network, the relative abundance of specialized species in the major modules of the experimental group increased, and the network complexity increased. The assembly of microbial communities in the two groups was mainly dominated by random processes, while ecological drift and homogeneous diffusion in the experimental group were less important for community construction, which made the microbial community succession more certain. This study revealed the ecological function of S. cerevisiae in Nongxiangxing baijiu fermentation, which could have an important impact on baijiu fermentation.

Key words: Nongxiangxing baijiu; Saccharomyces cerevisiae; niche; community succession