Difference of microbial community and gene composition with saccharification function between Chinese nongxiangxing daqu and jiangxiangxing daqu

BACKGROUND The saccharification function of daqu is usually characterized by two indicators: saccharification power and liquefaction power. Daqu provides diverse microbial saccharifying enzymes for hydrolyzing carbohydrate in Baijiu fermenting grain. Obviously, the composition of microbial communities and enzymatic genes in different types of daqu cultured at varied temperatures is different. However, these differences in saccharification function are not fully understood. RESULTS The findings suggested that the saccharification power and liquefaction power of jiangxiangxing daqu were lower than those of nongxiangxing daqu throughout the production process. We employed metagenomics to find evidence that a mode of multiple saccharifying enzymes involving amylase, cellulase and hemicellulase originating from various microbes exists in daqu. Moreover, a totality of 541 related differential genes were obtained, some of which, annotated to genera of Aspergillus, Lactobacillus and Weissella, were significantly enriched (P < 0.05) in nongxiangxing daqu, while others, annotated to thermophilic genera of Virgibacillus, Bacillus, Kroppenstedtia and Saccharopolyspora, showed a higher relative abundance in jiangxiangxing daqu (P < 0.05). CONCLUSION Various microbial communities of daqu showed diverse saccharification capacity during cultivation of different parameters. These findings are helpful in comprehending the saccharification functional genes of daqu. (c) 2022 Society of Chemical Industry.

Automated summary

The saccharification power and liquefaction power of different types of daqu were found to vary, with microbial saccharifying enzymes from various microbes playing a role in the process. The study identified differential genes and highlighted the differences in microbial communities between daqu types, providing insights into the saccharification functional genes of daqu.