Metagenomic analysis reveals the correlations between microbial communities and flavor compounds during the brewing of traditional Fangxian huangjiu

Fangxian huangjiu (FH) is the representative of xiaoqu huangjiu and is made from glutinous rice and traditional Fangxian huangjiu xiaoqu. This study investigated the correlations among microbial communities, physicochemical factors, and flavor compounds during the fermentation of traditional FH. Ethanol, amino nitrogen, and total acidity were the top three physicochemical factors closely related to the structure of the microbial community. A comprehensive analysis identified 10 organic acids, 18 amino acids, and 89 volatile compounds in FH. Notably, 28 of these volatile compounds, including 9 esters, 2 alcohols, 5 acids, and 2 aromatic compounds, were identified as the compounds responsible for the characteristic aroma of FH. The metabolic pathway of the flavor compounds was mapped, which primarily involved alcohols and esters. Moreover, microbial contributions to starch degradation and flavor formation were investigated using metagenomic sequencing data. The microorganisms involved in starch degradation primarily included Rhizopus, Mucor, Saccharomycopsis, Lactococcus, Lactobacillus, Lactiplantibacillus, and Leuconostoc. The microorganisms involved in flavor formation primarily included Rhizopus, Mucor, Saccharomyces, Wickerhamomyces, Cyberlindnera, Lactococcus, Leuconostoc, Acinetobacter, Enterobacter, and Lactiplantibacillus. The findings of this research offer valuable insights into the diverse metabolic functions of these microorganisms during fermentation and serve as a basis for the development of synthetic microbiota for FH brewing.