[Background] Environmental factors are important regulatory factors for the growth and metabolism of microorganisms. Therefore, the analysis of their influence on the succession of microbial communities in the fermentation process plays an important role in the controlled fermentation of highland barley Baijiu. As important nutrient substrates and environmental factors in microbial growth and metabolism, the effects of amino acids on microbial succession are still unclear. [Objective] To revealing the role of environmental factors in driving microbial community succession and flavor metabolism during highland barley Baijiu fermentation. [Methods] Gas chromatography-mass spectrometry was used to compare the changes of flavors during fermentation of dulihuang and walan fermented grains. High throughput sequencing and multivariate statistical analysis were used to compare the microbial structure characteristics in two kinds of fermented grains. The effects of environmental factors on microorganisms were determined by Mantel test and correlation analysis. The results were verified by simulated fermentation in vitro. [Results] The content of esters, amino acids and the relative abundance of Lactobacillus in dulihuang fermented grains was significantly (P<0.05) lower than that in walan. Through bioinformatics analysis, it was found that the content of free amino acids drove the microbial succession during the fermentation process, and the relative abundance of Lactobacillus was significantly correlated with the content of free amino acids. In vitro validation confirmed that the lack of amino acids can affect the growth of Lactobacillus. [Conclusion] The study revealed the driving effect of free amino acids on the assembly of microbial community in the process of highland barley Baijiu, and further affected the flavor quality, laying a foundation for the controlled brewing of highland barley Baijiu.
