Abstract: In this study, high-throughput sequencing was used in combination with mathematical statistical analysis to analyze the succession of bacterial community structure during the mechanized fermentation of Maotai-flavor Daqu. The results showed that the dominant bacteria during the fermentation process were Firmicutes, Proteobacteria, Actinobacteria and Cyanobacteria. As fermentation progressed, Firmicutes became the single dominant phylum. A total of 84 bacterial genera were detected during the mechanized fermentation process, and 82 bacterial genera during the traditional fermentation process. Of the 84 genera, 14 were dominant, including Pantoea, Rhizobium, Lactobacillus, Weissella, Bacillus, Oceanobacillus, Lentibacillus, Kroppenstedtia, Thermoactinomyces, Staphylococcus, Enterobacter, Saccharopolyspora, Leuconostoc and Pseudomonas, of which Pantoea, Rhizobium, Lactobacillus, Weissella, Bacillus, Oceanobacillus, Lentibacillus, Kroppenstedtia, Thermoactinomyces, Staphylococcus, Enterobacter, Saccharopolyspora, Pediococcus and Tepidimicrobium. Pediococcus and Tepidimicrobium were dominant exclusively during the mechanical fermentation process, while Leuconostoc and Pseudomonas were dominant exclusively during the traditional fermentation process. Accordingly, there was a high similarity in the dominant bacteria between the mechanized and traditional fermentation processes. The correlation analysis of the dominant bacteria and environmental factors indicated that the major functional genera Bacillus, Lactobacillus and Weissella were positively correlated with Daqu fermentation temperature and acidity, indicating that during the mechanized fermentation process, the temperature and acidity should be controlled reasonably and scientifically to promote the growth of the major functional bacteria and simultaneously inhibit the multiplication of heat-resistant and acid-tolerant bacteria. This study corroborates that the mechanized fermentation process can be an alternative to the manual fermentation process from the perspective of the structure of bacterial community, which will lay the scientific foundation for the theoretical research and industrial application of the mechanized Maotai-flavor Daqu-making process.

Key words: Maotai-flavor Daqu; mechanized Daqu making; high-throughput sequencing; bacterial community structure