Abstract: In this study, the 16S rDNA fragments of bacteria in fermented grains from seven rounds of stacking fermentation in Maotai-flavor liquor mechanized brewing were sequenced and analyzed by high-throughput sequencing technology. The results showed that a total of 14 phyla and 456 genera were detected in the seven rounds. Proteobacteria, Actinobacteria, and Firmicutes were the dominant phyla. The core bacteria were Acinetobacter, Bacillus, Caulobacter, Kroppenstedtia, Lactobacillus, Lentibacillus, Oceanobacillus, Pediococcus, Rhodococcus, Sphingomonas, Thermoactinomyces and Weissella. Both Caulobacter and Rhodococcus were the unique genera of bacteria in the process of mechanized brewing, which may come from the mechanical equipment or environment. The core microorganisms were interrelated to each other, including the symbiotic bacteria Bacillus, Lactobacillus, Thermoactinomyces, Lentibacillus, Kroppenstedtia, Weissella, Pediococcus and Oceanobacillus, while Acinetobacter, Caulobacter and Philingomonas were negatively correlated with the other nine genera. Among the fermentation environmental factors, moisture, acidity and starch content had great influence on the microbial community structure. Bacillus, Thermoactinomyces and Pediococcus were positively correlated with starch content and negatively correlated with moisture and acidity. Caulobacter and Sphingomonas were negatively correlated with starch content and positively correlated with moisture, and Sphingomonas was also positively correlated with acidity. The core bacterial community in the process of mechanized fermentation of Maotai-flavor liquor revealed in this study lays a scientific foundation for further theoretical research and engineering application of mechanized fermentation of Maotai-flavor liquor.

Key words: Maotai-flavor liquor, mechanization, high-throughput sequencing, microbial community and structure, stacking fermentation, core bacterial community