Bacterial and fungal diversity in the traditional Chinese strong flavour liquor Daqu

• Published in: Journal of the Institute of Brewing Vol. 125; no. 4; pp. 443 - 452
• Main Authors: Shoubao, Yan, Xiangsong, Chen, Jiaquan, Guang
• Format: Journal Article
• Language: English
• Published: London Wiley Subscription Services, Inc 2019
• Subjects: Amylases; Bacteria; Breweries; Brewing; Chinese strong flavour liquor; Correlation analysis; Daqu; Distillation; Dominance; Electrophoresis; Esterase; Fermentation; Flavor; Flavors; Fungi; Gel electrophoresis; Glucoamylase; Microbial activity; microbial community; Microorganisms; Moisture; Nitrogen; PCR‐DGGE; Physicochemical properties; Polymerase chain reaction; Protease; Proteinase; rRNA 16S; Starch; Yeast; Yeasts; α-Amylase
• ISSN: 0046-9750; 2050-0416
• DOI: 10.1002/jib.574

In this study, the diversity of bacterial and fungal communities in the strong flavour Daqu production process was investigated using polymerase chain reaction denatured gradient gel electrophoresis (PCR‐DGGE). The band number, dominance, diversity and similarity of the 16S rDNA differed in the DGGE patterns, reflecting the wide diversity of the microbial communities present in the different phases. The band abundance and dominance of the eukaryotic microbial community varied in the different phases. To provide insight into factors contributing to this diversity, the physicochemical properties of Daqu were explored. The core temperature of Daqu gradually increased to a maximum during the Dinghuo phase followed by a decline. The moisture and starch content decreased throughout fermentation. The total acid, reducing sugar, amino nitrogen, α‐amylase activity, glucoamylase activity, protease activity, bacterial and mould number increased gradually to a maximum value at the end of the Peijun phase before decreasing in the Dinghuo phase increasing slightly in the Huanluo phase and then remaining almost unchanged. The esterase activity exhibited a similar change to that of other enzymes and then slightly increased after the Peijun stage. For yeasts, the highest number was obtained at the Peijun stage and then decreased. Correlation analysis revealed that the diversity of both bacteria and fungi was negatively correlated with moisture and starch and positively correlated with other indices. The reducing sugar, amino nitrogen, α‐amylase and protease activities showed significant positive correlation with bacteria, and glucoamylase and esterase showed significant correlation with fungi. © 2019 The Institute of Brewing & Distilling