Understanding of microbial diversity in three representative Qu in China and characterization of the volatile compounds in the corresponding Chinese rice wine

Microbial diversity of three typical Qu in China, Jimo wheat Qu from Shandong province (WQJM), Shaoxing wheat Qu from Zhejiang province (WQSX), and Gutian Hong Qu from Fujian province (GTHQ), was compared by Illumina-based sequencing. Then volatile compounds in rice wine were analyzed by FlavourSpec (R) to illustrate correlation between rice wine flavor and microbes in Qu. Results showed that the microbial diversity was WQJM > WQSX > GTHQ, and the dominant microbiota in each Qu varied greatly. Saccharopolyspora, Staphylococcus and Aspergillus were the main microorganisms in WQSX. Microbes in WQJM distributed relatively even, and Pantoea, Bacillus, Pediococcus, Staphylococcus, Weissella, Aspergillus, Rhizopus, Thermoascus, and Saccharomyces were dominated. In GTHQ, Pantoea, Klebsiella, Burkholderia, and Monascus were major microbial floras. Correlation analysis indicated that Corynebacterium, Klebsiella, Pantoea, Wickerhamomyces, and Mucor in WQSX were mainly correlated with producing esters including ethyl hexanoate, isoamyl acetate, ethyl pyruvate. Brevibacterium, Klebsiella, Brachybacterium, Aspergillus, Penicillium, and Xeromyces in WQJM were strongly related with aldehydes, alcohols and ketones represented by benzaldehyde, ethanol, heptan-2-one. In GTHQ, Burkholderia, Weissella, Aspergillus, Candida, Davidiella, Alternaria and Saccharomyces were closely correlated with butan-1-ol, 2-pentanone, dimethyl sulfide. The different microbiota in Qu caused variation of metabolism during brewing, and lead to the distinguished flavor of rice wine.

Automated summary

The microbial diversity of three typical Chinese Qu varieties was compared using Illumina-based sequencing, showing different dominant microbiota in each Qu. These variations in microbial composition led to differences in fermentation metabolism, ultimately resulting in distinct flavors of rice wine.