AUTHOR=Deng Ling , Mao Xiang , Liu Dan , Ning Xin-Qiang , Shen Yi , Chen Bo , Nie Hong-Fang , Huang Dan , Luo Hui-Bo 

TITLE=Comparative Analysis of Physicochemical Properties and Microbial Composition in High-Temperature Daqu With Different Colors

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.588117

DOI=10.3389/fmicb.2020.588117

ISSN=1664-302X

ABSTRACT=<p>High-temperature <italic>Daqu</italic>, also called Jiang-flavor <italic>Daqu</italic>, is the saccharifying and fermenting agent for brewing Jiang-flavor Baijiu. During the spontaneous solid-state fermentation of high-temperature <italic>Daqu</italic>, variations in temperature and moisture lead to microbial diversity and various metabolites, contributing to the different colors of high-temperature <italic>Daqu</italic> (customarily referred to as white <italic>Daqu</italic>, black <italic>Daqu</italic>, yellow <italic>Daqu</italic>, and red <italic>Daqu</italic> in production). We aimed to investigate the differences in microbial communities, physicochemical indices, and potential functions among different high-temperature <italic>Daqu</italic> with different colors (labeled as QW, QB, QY, and QR) by amplicon sequencing. We found that <italic>Kroppenstedtia</italic>, <italic>Bacillus</italic>, and <italic>Thermoascus</italic> were predominant in all samples; <italic>Saccharopolyspora</italic> and <italic>Thermomyces</italic> were predominant in QB and QR; and <italic>Unclassfied_O_Eurotiales</italic> were predominant in QY. The results on the physicochemical characteristics indicated that compared with other <italic>Daqu</italic> samples, QW exhibited higher protease activity and lower acidity, whereas QB showed the opposite results. QR had the highest esterification yield, and QY exhibited the highest saccharification but lowest esterification yield. Functional prediction demonstrated that the higher abundances of genes encoding bacterial enzymes of QW and QY were related to the considerably higher abundances of <italic>Kroppenstedtia</italic> in QW (59%) and QY (87%), respectively. The highest abundance of <italic>Thermomyces</italic> in QB (80%) contributed to the highest abundance of genes encoding fungal enzymes in QB. This study revealed the microbial and functional dissimilarities of color-based high-temperature starters and helped facilitate the liquor fermentation process.</p>