Effects of Environmental Factors on Diversity of Bacterial Communities in Different Fermentation Rounds in Maotai Town

The bacterial community structure in different fermentation rounds in Maotai town was analyzed by MiSeq high-throughput sequencing combined with SPSS statistical software 26.0 and the environmental effect on it was evaluated. A total of 33 bacterial classes, 153 families and 396 genera were identified, among which, the dominant classes were Gammaproteobacteria, Bacilli, Sphingobacteriia, Alphaproteobacteria, Actinobacteria, Flavobacteriia and Betaproteobacteria. Totally 19 dominant families were found, including Enterobacteriaceae, Sphingobacteriaceae, Bacillaceae, Flavobacteriaceae, Thermoactinomycetaceae, and Planococcaceae. Among them, Flavobacteriaceae, Planococcaceae, Bacteroidales_S24-7_group, Microbacteriaceae and Brucellaceae were considered as the dominant bacterial families for the first time in baijiu-making environments. A total of 22 dominant genera were identified, including Sphingobacterium, Enterobacter, Pantoea, Acinetobacter, Oceanobacillus and Pseudomonas. The correlation of environmental factors (temperature, humidity, precipitation, sunlight and atmospheric pressure) with the alpha diversity and the 48 dominant bacterial classes, families and genera was analyzed by t-test combined with Spearman correlation analysis. The results showed that the alpha diversity was significantly correlated with environmental factors, and the environmental bacterial communities in the 2nd and 3rd rounds of fermentation had a significant correlation with temperature and humidity. In addition, 35 dominant bacteria had a significant correlation with environmental factors; among them, Gammaproteobacteria and Bacilli as well as their respective subclasses were significantly correlated with the five environmental factors, especially temperature, humidity and sunlight. Alphaproteobacteria and its subclasses had a significantly positive correlation with environmental temperature. Sphingobacteriia, and its Sphingobacterium genus had a significant correlation with temperature and precipitation. Actinobacteria and its subclasses were significantly positively correlated with light duration. Betaproteobacteria and Flavobacterium as well as their respective subclasses were almost not affected by environmental factors. The results of this study provide a basic theoretical and disciplinary basis for the in-depth understanding of the microbial community structure characteristics in the brewing environment of Maotai town and their correlation with environmental factors.