Community dynamics and assembly is driven by environmental microbiota mediated by spatiotemporal distribution: The case of Daqu fermentation.

In almost all environments, microbial interaction is shaped by differences in environmental microbial transport, resulting in synergistic or antagonistic effects among community members. Unfortunately, the current understanding of how environmental microbiota affect spontaneous fermentation is very limited. Here, we selected Daqu workshops with different usage times (named X (60 years), Y (10 years), and Z (0 year)) as research model. The microbial contribution of raw material and environments to the microbiota of Daqu fermentation among workshops was compared, raw material microbiota contributed more bacterial genera (44.70 %-73.56 %) to the fermentation, and environmental microbiota contributed more fungal genera (10.09 %-99.76 %) to the fermentation. The deterministic assembly ratio and interaction intensity of workshop X were the highest, followed by Y and Z. We analyzed the relationship between environmental microbiota, fermentation microbiota, fermentation characteristics and flavor compounds. Environmental microbiota negatively drove the microbial diversity during fermentation (path coefficient = -1, P = 0.004), and further indirectly affected the community dynamics and assembly (path coefficient = -0.990, P < 0.001). Finally, community dynamics and assembly drove flavor compound diversity (path coefficient = 0.923, P < 0.001), it indicated the positive effect of environmental microbiota on flavor compound diversity. This work will help to understand the relationship between environmental microbiota and fermentation quality, supporting quality improvement of spontaneously fermented food in new workshop.