Abstract: In this study, the microbial community structure in fermented grains from the upper middle and lower layers of the cellar in the first and second rounds of fermentation of Maotai-flavor was analyzed by high-throughput sequencing, and the acid composition by ultra-high performance liquid chromatography (UPLC). Moreover, the correlation between them was investigated. The results showed that the total acid content of fermented grains was greater in the second round than the first round of fermentation. The radial distribution patterns of seven acidic compounds in different times and spaces of the cellar were different. The contents of lactic acid and acetic acid accounted for a large proportion in the two rounds of fermentation. For both rounds, the absolutely dominant bacterial genus was Limosilactobacillus, and the dominant fungal genera were Saccharomyces and Candida. As the fermentation time extended, there was a significant difference in the microbial community structure. The contents of total and individual acids were positively correlated with the relative abundance of Limosilactactacillacus, Schizosaccharomyces, Zygosaccharomyces, Candida and Kazachstania, and negatively correlated with the relative abundance of Lactobacillus, Saccharomyces, Paecilomyces and Torulaspora. This study provides a theoretical basis for further elucidating the fermentation mechanism of Maotai-flavor Baijiu cellar.

Key words: Maotai-flavor Baijiu; fermented grains; acids; microbial community; correlation