Physicochemical indicators and microbial community structure of fermented grains during the fermentation process of strong-flavor Baijiu with different pit ages

The physicochemical indicators and microbial community structure of the fermented grains of strong-flavor (Nongxiangxing) Baijiu in 5-year and 50-year pits (a5, a50) during fermentation process were detected by conventional detection methods and high-throughput sequencing techniques, and the correlations between them were analyzed through co-linearity network analysis. The results indicated that the physicochemical indicators of samples in pits with different ages were all within the appropriate range. The richness and diversity of the fungal community in the a50 sample were both higher than those in the a5 sample at fermentation 60 d, while the bacterial community was the opposite. During the fermentation process, although the main dominant bacterial genera of the fermented grains in pits with different ages were Lactobacillus, Thermoactinomyces, Staphylococcus and Kroppenstedtia, the bacterial community succession in a50 sample was more rapid. The main fungal genera in a50 sample were Beauveria, Acremonium, Saccharomycopsis and Rhodotorula, while were unclassified-k-fungi, Alternaria, Kazachstania, and Didymella in a5 sample. The physicochemical factors drove the microbial community succession during the fermentation process of fermented grains in pits with different ages. This study was helpful to reveal the microbial community composition and differences during the fermentation process of fermented grains in pits with different ages, and provided a basis for continuous optimization of fermented grains in new pits and oringinal liquor quality.