Effects of distilled grains on environmental factors and microbial communities in the fermentation of light flavor Baijiu

Abstract:

[Background] Environmental factors affect the microbial growth and metabolism. Therefore, understanding their influences on microbial community succession in the semi-open fermentation process is of great significance for the production regulation of light flavor Baijiu. Distilled grains play a role in regulating the fermentation speed of Baijiu, while their effects on microbial community succession are still unclear. [Objective] To reveal the effects of distilled grains fermented for different time periods on the environmental factors and microbial community succession during light flavor Baijiu fermentation. [Methods] The high-throughput sequencing on PacBio platform and multivariate statistical analysis were performed to reveal the microbial community structures in two different groups of fermented grains. Monte Carlo permutation tests were conducted to determine the effects of environmental factors on microorganisms. [Results] The fermented grains prepared with distilled grains produced in extended fermentation period (EG) had lower water content and higher acidity, amino acid nitrogen, total free amino acids, reducing sugar, and residual starch than those prepared with distilled grains produced in normal fermentation period (NG). The fermented grains with EG had higher bacterial alpha diversity (P<0.001) and lower fungal alpha diversity than those with NG (P<0.05, P<0.001). A total of 28 differential bacterial indicator species and 15 differential fungal indicator species between groups were identified. Water content, acidity, amino acid nitrogen, reducing sugar, residual starch, and total free amino acids had effects on the microbial community structure (P<0.05). Among them, water content, acidity, amino acid nitrogen, and total free amino acids were associated with the microbial community of fermented grains with EG, and reducing sugar and residual starch were the main driving factors for the microbial community succession of fermented grains with NG. [Conclusion] The effects of environmental factors on microbial community assembly in the fermentation process of light flavor Baijiu with distilled grains produced in different fermentation periods were revealed, laying a foundation for the controlled brewing of light flavor Baijiu.