Differences in structure, volatile metabolites, and functions of microbial communities in Nongxiangxing daqu from different production areas

Abstract

Nongxiangxing Baijiu is a liquor widely consumed in China and whose flavor vary considerably depending on the production area. Daqu is a common fermentation starter for Baijiu production and significantly affects the flavor of Nongxiangxing Baijiu. The present study aimed to evaluate differences in the structure and potential functions of the microbial communities, as well as in volatile metabolites of Nongxiangxing daqu samples obtained from different production areas. A total of 36 different microorganisms were found in daqu from five production areas in China. Saccharopolyspora, Pantoea, Pediococcuss, Thermomyces, Issatchenkia, and Saccharomycopsis could be considered as biomarkers to discriminate daqu origin based on production area. Moreover, 41 differential metabolites were found based on PLS-DA analysis. Co-occurrence network analysis indicated that the abundance of most differential microorganisms was significantly correlated with changes in differential volatile metabolites in daqu. Function prediction of microbial communities and pathway enrichment analysis of differential metabolites further revealed differences in the functions of daqu samples from different production areas, especially related to amino acid metabolism, fatty acid metabolism, and carbon metabolism. Collectively, the results described herein provide a theoretical basis for the understanding of differences in the flavor of Nongxiangxing Baijiu from distinct production areas.