Insight into the succession pattern of the microbial community of fermented grains and driving forces during pit fermentation of Maotai-flavor baijiu.

Microbial successions during pit fermentation are critical for flavors synthesis of Maotai-flavor baijiu (MFB). The present study aimed to explore microbial succession patterns and associated driving forces in the 4th round fermented grains (FG). Results showed that Oceanobacillus, Virgibacillus, Kroppenstedtia, Bacillus, Lactobacillus, Zygosaccharomyces, Issatchenkia, and Pichia were identified as core microbes and 25 key flavors were determined. The pit fermentation process was further delineated into the initial phase and subsequent phase. Core microbes except Lactobacillus and Zygosaccharomyces driven by reducing sugar, pH, liquefying power, and saccharifying power showed positive correlations with 3-methyl-1-butanol and/or furfural (furfuryl alcohol) in the initial phase. However, primarily influenced by acidity and moisture, Lactobacillus and Zygosaccharomyces produced benzyl alcohol, ethyl benzoate and ethyl phenylacetate in the subsequent phase. Together, our study revealed the clear phase character of FG during pit fermentation and biotic/abiotic factors influenced microbial successions, providing valuable knowledge for targeting regulation of key flavors.