Microbial community structure and interactions between Aspergillus oryzae and bacteria in traditional solid-state fermentation of Jiangqu

Microbial interactions play an important role in the formation, stabilization and functional performance of natural microbial communities. However, little is known about how the microbes present interactions to build a stable natural microbial community. Here, we developed Jiangqu, the solid-state fermented starters of thick broad-bean sauce formed naturally in factory, as model microbial communities by characterizing its diversity of microbial communities and batch stability. The dominant microbial strains and their fungi-bacteria interactions during solid-state fermentation of Jiangqu were characterized. In all batches of Jiangqu, Aspergillus oryzae, Bacillus, Staphylococcus and Weissella dominated in the communities and such a community structure could almost reduplicate between batches. Direct adsorption and competition were identified as the main interactions between A. oryzae and dominant bacteria during solid-state fermentation, which were quite different from liquid cocultivation of A. oryzae and dominant bacteria. These results will help us better understand the intrinsic mechanism in the formation and stabilization of microbial communities from traditional solid-state qu-making and fermentation.

Automated summary

Microbial interactions are crucial for the formation, stabilization, and performance of natural microbial communities. However, little is known about the specific interactions that lead to the establishment of stable microbial communities. This study focused on the solid-state fermentation of Jiangqu, a naturally-formed thick broad-bean sauce, to investigate its microbial diversity and batch stability. The dominant microbial strains, including Aspergillus oryzae, Bacillus, Staphylococcus, and Weissella, were identified, and their interactions during fermentation were characterized. The findings highlight the importance of direct adsorption and competition as key interactions in solid-state fermentation, contrasting with liquid cocultivation methods.