Comparative analysis of metagenomics between high- and medium-temperature daqu, and microbial succession in Jiang-Nong Jianxiang Baijiu fermentation.

Abstract

Background: The mixture of high-temperature Daqu and medium-temperature Daqu can be used to produce Chinese Jiang-Nong Jianxiang Baijiu. This study used metagenomic sequencing and physicochemical analysis to investigate the microbial community and functionality of high-temperature Daqu and medium-temperature Daqu. In addition, exploring the changes of microbial communities during the Jiang-Nong Jianxiang Baijiu fermentation process.

Results: The results showed that Lichtheimia ramose and Saccharopolyspora rectivirgula were the significantly different species in high-temperature Daqu. However, Paecilomyces variotii, Aspergillus chevalieri, and Rasamsonia emersonii were the significantly different species in medium-temperature Daqu. The medium-temperature Daqu had higher saccharifying power (101.20 ± 1.85 U/g) than high-temperature Daqu (60.00 ± 0.58 U/g). And the protease activity of high-temperature Daqu (62.47 ± 5.84 U/mg) was significantly higher than medium-temperature Daqu (36.10 ± 1.13 U/mg). The community structure analysis results of the stack fermentation stage showed that the mixture of high-temperature Daqu and medium-temperature Daqu inherited the community advantages of both high-temperature Daqu and medium-temperature Daqu. With Jiang-Nong Jianxiang Baijiu fermentation, the significantly different species changed from Pichia sp., Acetobacter sp., and Lactobacillus sp. to Pediococcus sp., Lactobacillus sp., Lentilactobacillus sp., Saccharomyces sp., Thermoactinomyces sp., and Saccharopolyspora sp., implying the importance of acid-resistant and ethanol-resistant microorganisms for the production of flavor substances in the late Baijiu fermentation.

Conclusions: Our research revealed the difference in microbial communities between high-temperature Daqu and medium-temperature Daqu, and demonstrated the shifts and functionality of microbiota during Jiang-Nong Jianxiang Baijiu fermentation. This study provides a theoretical reference for utilizing core synergistic microbiota and their functional traits in Baijiu fermentation starters to improve Baijiu quality.