Multi-omics reveals microbial community characteristics and flavonoid biotransformation mechanisms during mung bean sour fermentation

Fermented foods are gaining popularity for their health benefits, and fermented mung bean products are recognized for their nutritional value. To investigate microbial community succession and abundance dynamics of bioactive compounds like flavonoids in fermented mung bean sour (MBS), parallel metagenomic and metabolomic analyses were performed. Metagenomic profiling identified Lactiplantibacillus , Lactococcus , Bifidobacterium , and Acetobacter as dominant genera. Functional gene analysis demonstrated a significant increase in the relative abundance of flavonoid degradation pathways, which exhibited strong positive correlations (r > 0.8, p < 0.05) with the dominant genera. Metabolomic analysis revealed a significant decrease in flavonoids, including vitexin and orientin. Moreover, increased activities of β-glucosidase and α-rhamnosidase were identified as key factors promoting the biotransformation of flavonoids into bioactive metabolites such as apigenin, naringenin, and quercetin. This study provides a foundation for further understanding the microbial conversion and utilization of flavonoid compounds in mung beans.