Traceability between microbial community and environmental microbial Community in Maotai-flavor Daqu

Maotai-flavor Daqu is an indispensable and important fermentative and saccharifying agent in the production of Chinese sauce-flavored baijiu. The diversity and complexity of its microbial community has a decisive impact on the quality and flavor of the baijiu. However, although some studies have provided preliminary analysis of the microbial composition in Daqu, the specific influence of environmental microbes on the Daqu production process, as well as the origin and formation mechanism of the Daqu microbial community, are still not clear. In addition, the production process of Daqu is an open natural fermentation process. Microorganisms from the environment can enter Daqu through various pathways such as air, soil, and raw materials, thereby affecting its microbial community structure. To investigate the source of the microbial community in Maotai-flavor Daqu and the impact of environmental microorganisms on the Daqu production process, air was collected from inside and outside the Daqu room, soil from the external environment, Daqu wheat, rice straw, and Daqu at different stages. High-throughput sequencing was used to detect bacteria and fungi in all samples. Finally, with Daqu at different periods as the target for tracing and the other samples as the objects for tracing, Source Tracker was employed to conduct a tracing analysis of Daqu. The results showed that the richness and diversity of microorganisms in the samples decreased gradually from the outside to the inside. The microbial community structure in the soil in the external environment was quite different from that of other samples, and its contribution to the community in Daqu was small. Qu wheat and rice straw made a great contribution to Daqu. The findings of this study show that the environment and raw materials affect the quality of Daqu, and the change in microflora in the fermentation process of Daqu is determined by both the environment and raw materials.