The priority effect of microbial community on the initiation of Chinese rice wine fermentation and flavor formation

The fermentation and flavor development in Huangjiu (Chinese rice wine) are driven by the ecological succession of various microorganisms, including lactic acid bacteria and Saccharomyces cerevisiae. Here, isolated in-situ microorganisms from Huangjiu fermentation environments to explore the priority effects of bacterial community on the initiation of fermentation and the formation of flavors. Employing an experimental strategy that involved constructing synthetic communities, the result show that specific bacterial combinations exerted positive priority effects on the initiation of fermentation and the production of flavor compounds. A meta-analysis of public Huangjiu datasets revealed that bacterial community assembly fluctuate the most during the pre-fermentation stage. In-situ and co-culture experiments indicated that the spatial structure of solid-liquid mixing and the ability to hydrolyze peptides were crucial for stable microbial colonization at the pre-fermentation stage, leading to the degradation of over 44 % of fermentation substrates. Moreover, more than 80 % of the observed interactions among bacterial community members were non-competitive during this phase. The study found that synthetic communities of L. plantarum and L. fermentum boosted S. cerevisiae biomass by over 30 % by promoting free amino acid accumulation. The community not only enhanced the characteristic flavor compounds of Huangjiu but also diminished the levels of harmful endogenous substances. Interestingly, only 12 % synthetic communities (25 combination, up to 5 members) exhibited positive priority effects, underscoring the specificity of community assembly functions. The work findings emphasize the critical role of microbial priority effects in initiating Huangjiu fermentation.