Bioturbation effect of fortified Daqu on microbial community and flavor metabolite in Chinese strong-flavor liquor brewing microecosystem

Traditional spontaneous fermentation in microecosystem with microbial successions and environmental variables results in inconsistent quality of fermented foods. We therefore propose the directional bioturbation for microbiota regulation and metabolites production in food fermentation. Here, we revealed the bioturbation effect of fortified Daqu on microbial community based on taxonomic composition, co-occurrence network, and metabolic potential, using Chinese strong-flavor liquor fermentation as a microecosystem. According to principal coordinate analysis, microbial communities were obviously influenced by the bioturbation of fortified Daqu. More specifically, bioturbation increased the abundances of Caproiciproducens, Clostridium, Aspergillus, Candida, Methanobacterium, and Methanosarcina, while decreased that of Lactobacillus. Meanwhile, higher abundances of most genes that encoding enzymes involved in interspecies hydrogen transfer between hexanoic acid bacteria and methanogens were observed in the bioturbated ecosystem by PICRUSt approach. Additionally, co-occurrence analysis showed that bioturbation increased the diversity and complexity of interspecies interactions in microecosystem, which contributed to higher production of flavor metabolites such as hexanoic acid, ethyl hexanoate, and hexyl hexanoate. These results indicated that the bioturbation of fortified Daqu is feasible for flavor metabolism by interspecies interactions of functional microbiota in liquor fermentation. Taken together, it is of great importance for regulating Chinese liquor and even other foods fermentation by bioturbation.