Analysis of the Physicochemical Properties and Microbial Composition of Fenjiu Daqu During Daqu Making Processes

Daqu is an important raw material as a starter in the fermentation process, provides various microorganisms that required during the fermentation in the fermentation process. However, the microbial communities characteristics in different Daqu making stages need to be further studied. In this paper, three kinds of Daqu including Qingcha, Houhuo and Hongxin were selected as research material, the physicochemical properties and microbial communities were studied in four typical Daqu making stages including Qupei, Shangmei, Houhuo and Chufang stages. The total DNA was extracted using E.Z.N.A. Soil DNA Kit, and the microbial community characteristics were further analyzed based on polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). In the results, at each stage of Daqu production process, the physical and chemical properties, microbial numbers and enzyme activities among the three kinds of Daqu had few differences, while the composition of microbial community was in dynamic change. Specifically, combined with OTU analysis, it is found that the dominant bacteria in Daqu include 5 kinds of lactobacillus, as well as other bacteria of Thermoactinomyces , Streptococcus and Acetobacter . As for fungi, the identified at species level include 3 yeasts, as well as 4 genera including Aspergillus oryzae , Malassezia globosa , Saccharomycopsis , Pichia , and Thermoascus . In the different production stages of the three kinds of Daqu, the composition and structure of microbiology communities changed dynamically with the fermentation time, which may be affected by multiple factors such as temperature and environment. In conclusion, the physical and chemical properties and microbial community structure of Fenjiu Daqu in the Daqu making process was analyzed, and the changes of microbial diversity in different stages were preliminarily explored, which can provide a theoretical basis for further understanding and improving the quality of Fenjiu Daqu.