Evaluation of the spatial distribution and dynamic succession of microbial community and quality properties during fermentation in Chinese medium-temperature Daqu

The spatial characterization of qualities and microbial community of Chinese Baijiu Daqu during solid-state fermentation remains unclear. The physicochemical indexes and microbial of the core (CDB) and the surface (SDB) of medium-temperature Daqu (MT-Daqu) at eight fermenting stages were investigated. The results indicated the difference in physicochemical indices, enzymatic activities, and starch granule fracture between the CDB and SDB. The dominant bacteria were Lactobacillus, Weissella, Pediococcus, and Methylobacterium in the SDB, as Staphylococcus, Bacillus, Thermoactinomyces, and Undibacterium in the CDB. The dominant fungi were Dipodascus, Wickerhamomyces, Hyphopichia, and Saccharomyces in the SDB, like Aspergillus, Thermoacscus, Theromyces, and Candida in the CDB. Redundancy analysis (RDA) showed that different factors strongly affected the bacteria and fungi in the SDB and CDB, respectively. The temperature, moisture, and starch content were the critical factors for the microbial composition of Daqu. This study provides further valuable information for knowing the fermentation mechanism of MT-Daqu. Novelty impact statement This study provided information on the spatial characterization of qualities and microbial community of Chinese Baijiu Daqu during solid-state fermentation of medium-temperature Daqu (MT-Daqu). This study revealed the difference between the surface brick samples (SDB) and the core brick samples (CDB) in the fermentation process of Daqu, which increased the diversity of fermentation. The temperature, moisture, and starch content were the critical factors in influencing the difference between Daqu microorganisms of the core (CDB) and the surface (SDB) of medium-temperature Daqu (MT-Daqu).