Study on the regulatory mechanism of vinegar grains metabolism via different vinegar starters

Abstract

The application of biofortification technology in regulating the microbial community of Sichuan bran vinegar (SBV) to enhance its quality has garnered significant attention recently. Here, we utilized Cuqu fortified (JQ) by synthetic microbiota composed of two different strains to enhance SBV fermentation, while simultaneously revealing community succession and metabolic regulatory mechanisms. Compared to control samples, the fortified vinegar grains (ZJV) community exhibited a 1.60-fold increase in bacterial biomass during major stages. Dominant fungi dynamics in ZJV significantly shifted, with a notable increase in Monascus and Rasamsonia. Upregulation of enzymes involved in starch and cellulose degradation led to increased contents of volatiles, 4-ethylguaiacol (4-EG), and raw starch conversion rate in the fermented ZJV by 1.75 times, 40 times, and 21.92%, respectively. Biofortification boosted interspecies interactions, clustering functional microbes into a module. Functional bacteria served as connectors, enhancing fungal-bacterial communication, optimizing information and energy exchange, reducing primary metabolite accumulation like ethanol, and improving nutrient utilization and metabolic conversion for secondary metabolite synthesis. These findings establish crucial groundwork for the practical application of synthetic microbiota in various engineering applications.