Evolving the core microbial community in pit mud based on bioturbation of fortified Daqu

Abstract

Directional stress is an effective measure to evolve community structure and improve bioactivity of pit mud (PM). In this study, adding fortified Daqu in artificial PM (APM) was to disturb the microbial community and affect the metabolites furthermore. To evaluate the effect of fortified Daqu on culturing APM, microbial communities of APMs with/without adding fortified Daqu were investigated by fluorescence in situ hybridization and Illumina Miseq. These results indicated that microbes (Clostridium sp., Clostridium kluyveri, hydrogenotrophic methanogens, and acetotrophic methanogens) related to the production of key aroma compounds increased notably when fortified Daqu was added. Especially the hydrogenotrophic and acetotrophic methanogens increased by 5.19- and 4.63-fold after 30-days’ culture. Then metabolites (organic acids, volatile compounds) were also analyzed by HPLC and HS-SPME-GC-MS. Results showed that the content of butyric acid and hexanoic acid was significantly higher when adding fortified Daqu. What’s more, the proportion of esters and phenols were higher compared with the APM without adding fortified Daqu as well. The microbial compositions of APMs with/without adding fortified Daqu were observed in this study, which indicated the microbial community evolving in functional community in favor of liquor-brewing and suggested a novelty process was developed by disturbing the community diversity.

Effects of bio‐augmented Daqu on microbial community, aroma compounds and physicochemical parameters of fermented grains during the brewing of Chinese special‐flavor baijiu

“…Chen et al . also found that the abundance of Lactobacillus was increased at the later fermentation stage after inoculating bio‐augmented Daqu 29 . There was also no obvious change in the fungal community after day 6 of fermentation.…”

“…28 Chen et al also found that the abundance of Lactobacillus was increased at the later fermentation stage after inoculating bio-augmented Daqu. 29 There was also no obvious change in the fungal community after day 6 of fermentation. This result was also obtained by Cui et al 30 Temperature is a key factor in the structure of microbial communities during fermentation.…”

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

“…Daqu not only provides the microbial consortium, enzymes (e.g., α-amylase and glucoamylase), and partial raw materials for alcoholic fermentation, but also significantly contributes aroma compounds [2,3,[8][9][10][11][12]. Previous studies of Daqu mainly focused on its microbial community profile and enzyme composition [3,4,8,9,[13][14][15][16][17][18], the dynamics of microbial succession in the Daqu manufacturing process [19][20][21][22], the effects of fortified Daqu on the microbial composition and flavor ingredients of Baijiu [23][24][25][26][27], and how environmental factors (e.g., moisture, acidity, and temperature) affect the microbial structure and enzymatic activity of Daqu [6,15,28].…”