Microbial communities and their correlation with volatile compounds in starters of Chinese sweet rice wine

Chinese sweet rice wines (CSRW) are traditional, regionally distinct alcoholic beverages that are generally brewed with glutinous rice and fermentation starters. This study aimed to characterize microbial communities and volatile compounds of CSRW starters and explore correlations between them. The major volatiles in starters include 1-heptanol, 1-octanol, 2-nonanol, phenylethyl alcohol, 2-nonanone, acetophenone, and benzaldehyde. A total of 594 bacterial genera and 58 fungal genera, were identified in CSRW starters. Starter bacterial communities are dominated by Weissella, Pediococcus, and Lactobacillus, while Saccharomycopsis and Rhizopus predominate in fungal communities. NT2 had greater bacterial community richness and higher bacterial community diversity, while YC1 had greater fungal community richness and diversity. Carbohydrate and amino acid metabolism are the most active metabolic pathways in starters. In total, 15 important volatile compounds including alcohols, acids, aldehydes and esters were significantly positively correlated with 9 microbial genera (|r| > 0.7, p < 0.05), including five bacterial genera (i.e., Weissella, Pediococcus, Lactobacillus, Bacillus, and Nocardiopsis) and four fungal genera (i.e., Saccharomycopsis, Rhizopus, Wickerhamomyces, and Cyberlindnera), spanning 19 distinct relationships and these microorganisms were considered the core functional microorganisms in CSRW starters. The most important positive correlations detected between phenylethyl alcohol and Weissella or Saccharomycopsis and between 2-nonanol and Pediococcus. This study identifies strong correlations between microbial genera and volatile compounds, which can facilitate isolation and culture of these taxa for development of defined CSRW starters for targeted flavor profiles in future work and can serve as a reference for improving the aromatic qualiy of CSRW.