Microbial Community Affects Daqu Quality and the Production of Ethanol and Flavor Compounds in Baijiu Fermentation

Abstract

Daqu is a traditional starter for Baijiu fermentation and is produced by spontaneous fermentation of ground and moistened barley or wheat. The quality of Daqu is traditionally evaluated based on physicochemical and subjective sensory parameters without microbiological analysis. Here, we compared the physicochemical characteristics of qualified (QD) and inferior (ID) Daqu, their microbial communities based on plate counting and PacBio SMRT sequencing of rRNA gene libraries, and their impacts on Baijiu fermentation. The results showed that the glucoamylase and α-amylase activities of QD were significantly higher than those of ID. The counts of yeasts and relative abundances of functional microbes, especially the amylolytic bacterium Bacillus licheniformis and fungi Saccharomycopsis fibuligera and Lichtheimia ramosa, were significantly higher in QD than in ID. The laboratory-scale Baijiu fermentation tests showed that the relative abundances of the amylolytic microbes were higher in the QD than the ID fermentation set, resulting in more efficient fermentation, as indicated by more weight loss and higher moisture content in the former. Consequently, more glycerol, acetic acid, ethanol, and other volatile compounds were produced in the QD than in the ID fermentation set. The results suggest that Daqu quality is determined by, and can be evaluated based on, its microbial community.

Characterizing the Contribution of Functional Microbiota Cultures in Pit Mud to the Metabolite Profiles of Fermented Grains

“…The differences in α-diversity of the microbial communities are presented in Table 3 . The bacterial richness and diversity in DQ were higher than those in MC and FC, possibly due to the greater ease of colonization by bacteria in smaller habitats [ 32 , 33 ]. The fungal diversity in MC was higher than that in FC and DQ, with the latter exhibiting the lowest diversity.…”

Optimizing the Conditions of Pretreatment and Enzymatic Hydrolysis of Sugarcane Bagasse for Bioethanol Production

“…27,28 In addition, thermophilic bacteria such as Bacillus played an important role in liquor making. 29 In our previous study, a bacterium named Bacillus sp. EtOH, which produced ethanol and Baijiu aroma substances, was isolated from HTD of Danquan Baijiu.…”

“…Thermophilic bacteria can also ferment lignocellulosic hydrolysates . An adapted xylanolytic bacterium, namely, Thermoanaerobacter mathranii, could ferment xylose from wheat straw to ethanol. , In addition, thermophilic bacteria such as Bacillus played an important role in liquor making …”

“… 27 , 28 In addition, thermophilic bacteria such as Bacillus played an important role in liquor making. 29 …”

Relationship between dynamic changes of microorganisms in Qupi and the quality formation of Fengxiangxing Huairang Daqu

“…Moreover, researchers can obtain species-level species composition and better resolution of species annotation further using this technique. This technique has also been applied in the research of Daqu ( Zhang et al, 2022a ; Zhang Y. D. et al, 2022 ; Han et al, 2023 ). However, in-depth analysis of the primary functional microbial species in the Fengxiangxing Daqu system is still scarce.…”