Analysis of microbial community structure during the fermentation process of Dacha fermented grains of light-flavor Baijiu

Using Dacha fermented grains from light-flavor (Qingxiangxing) Baijiu as the research object, the fermented grains without propidium monoazide (PMA) treatment as the control group (DT group), and the fermented grains with PMA treatment as the experimental group (DV group), the microbial community structure of fermented grains during fermentation process was systematically analyzed by amplicon sequencing technology, and the differential bacterial communities in different fermented grains were analyzed by the linear discriminant analysis effect size (LEfSe). Alpha diversity analysis indicated that when the fermented grains was fermented for 7 d, the diversity and uniform distribution of viable bacteria and fungi in the fermented grains of DV group were both relatively low. Beta diversity analysis indicated that there were significant differences between the total microbial flora and the viable microbial flora (P<0.05). The dominant bacterial and fungal genera (relative abundance>1%) in the fermented grains of the DV and DT group were Lactobacillus, Pediococcus, etc. and Saccharomycopsis, Issatchenkia, Hanseniaspora etc., respectively, among which Lactobacillus and Saccharomycopsis were the bacterial and fungal genera with the highest average relative abundance in the fermented grains of the DV and DT group (32.3%, 42.4%; 11.3%, 58.9%). Compared with the fermented grains samples of DT group, the average relative abundance of bacterial genera Lactobacillus, Pediococcus and fungal genera Saccharomycopsis, Issatchenkia, Hanseniaspora, etc. in the fermented grains samples of DT group was lower. Based on the linear discriminant analysis (LDA) values and variance analysis results, the differential microbial community of the two groups of fermented grains were Saccharomycopsis and Issatchenkia (LDA value>4.0, P<0.01).