Analysis of microbial diversity and functional differences in different types of high‐temperature Daqu

Abstract

Bacterial communities that enrich in high‐temperature Daqu are important for the Chinese maotai‐flavor liquor brewing process. However, the bacterial communities in three different types of high‐temperature Daqu (white Daqu, black Daqu, and yellow Daqu) are still undercharacterized. In this study, the bacterial diversity of three different types of high‐temperature Daqu was investigated using Illumina MiSeq high‐throughput sequencing. The bacterial community of high‐temperature Daqu is mainly composed of thermophilic bacteria, and seven bacterial phyla along with 262 bacterial genera were identified in all 30 high‐temperature Daqu samples. Firmicutes, Actinobacteria, Proteobacteria, and Acidobacteria were the dominant bacterial phyla in high‐temperature Daqu samples, while Thermoactinomyces, Staphylococcus, Lentibacillus, Bacillus, Kroppenstedtia, Saccharopolyspora, Streptomyces, and Brevibacterium were the dominant bacterial genera. The bacterial community structure of three different types of high‐temperature Daqu was significantly different (p < .05). In addition, the results of microbiome phenotype prediction by BugBase and bacterial functional potential prediction using PICRUSt show that bacteria from different types of high‐temperature Daqu have similar functions as well as phenotypes, and bacteria in high‐temperature Daqu have vigorous metabolism in the transport and decomposition of amino acids and carbohydrates. These results offer a reference for the comprehensive understanding of bacterial diversity of high‐temperature Daqu.

Understanding the Shifts of Microbial Community and Metabolite Profile From Wheat to Mature Daqu

“… Du et al (2019) proved that both the raw materials and the environments acted as important sources for Daqu microbiota ( Du et al, 2019 ). Because of the relatively open processing environment and the barefoot stepping process by women, there might be some microbiota such as Staphylococcus originating from the environment or women’ feet in Daqu ( Wang et al, 2021 ). During maturation, it was gradually inhibited by Kroppenstedtia ( He et al, 2019 ).…”

“…Particularly, fermentation plays an important role in the production of volatile flavors and critical secondary metabolites ( Zheng et al, 2011 ). Daqu , made of wheat, barley, pea, and/or corn, is the most common starter and adopted in all the famous Baijiu in China ( Wang et al, 2021 ). Daqu production needs a series of steps, including moistening, breaking, mixing shaping, spreading, incubating, and maturation ( Zheng et al, 2011 ).…”

The Fungal Communities and Flavor Profiles in Different Types of High-Temperature Daqu as Revealed by High-Throughput Sequencing and Electronic Senses

“…This complex solid-state fermentation process is repeated for seven cycles in an open and uncontrolled environment with multi-microorganisms ( Li et al, 2016 ; Du et al, 2019 ; Liu et al, 2019 ). These microorganisms have a major impact on fermentation yield and quality, mainly derived from HTD, a saccharifying starter, and raw material used in the brewing process of SFB ( Li et al, 2017 ; Yang et al, 2018 ; Wang Y. R. et al, 2021 ). HTD is composed of pea and barley along with wheat as primary raw materials and is made by shaping, piling, fermenting, and ripening under high temperature conditions (60–70°C) ( Li et al, 2016 , 2017 ; Fan et al, 2018 ).…”

“…On the basis of the different colors produced after browning, the HTD was mainly classified into three types (white HTD, black HTD, and yellow HTD). White HTD is mainly located at the top of the Daqu pile, accounting for 10–15% of total HTD; black HTD is mainly located in the middle of the Daqu pile, accounting for <1% of the total HTD; whereas yellow HTD is uniformly dispersed in the Daqu pile, accounting for 80–85% of the total HTD ( Gan et al, 2019 ; Wang Y. R. et al, 2021 ). During practical production, these three types of HTD are generally mixed and ground in a certain ratio for SFB fermentation ( Wang Y. R. et al, 2021 ).…”

Correlation: Between Autochthonous Microbial Diversity and Volatile Metabolites During the Fermentation of Nongxiang Daqu

“…Previous research found that the proportion of bacteria and fungi from Daqu was 81.5% and 79.2% respectively, in the fermented grain ( Wang P. et al, 2017 ). They not only affect the accumulation of enzymes in the fermentation process but also determine the final community composition ( Wang et al, 2021 ). Therefore, the Daqu microorganism group has a crucial effect on the quality formation of Nongxiang Baijiu.…”