Predicted Functional Profiles of Bacterial and Fungal Communities in Traditional Glutinous Rice Fermentation

This study investigated how predicted bacterial metabolic potential and fungal ecological roles vary across key stages of traditional Vietnamese fermented glutinous rice (com ruou) fermentation. Amplicon sequencing of 16S ribosomal RNA (16S rRNA) and Internal Transcribed Spacer (ITS) markers from Men, CR36H, and CR72H samples was used to characterize microbial communities and infer community-level functions. A conserved core of bacterial functions related to carbohydrate, amino acid, energy, and genetic information processing was detected across all samples, whereas stage-dependent shifts in specific enzymes and pathways suggested functional adjustment during fermentation. Comparison with previous rice-wine studies indicates that the predominance of central carbon metabolism, pyruvate conversion, and alcohol/organic acid-associated pathways is consistent with the starch-rich substrate and with known flavor-forming processes in glutinous rice fermentations. Fungal data were interpreted mainly as ecological support for saccharification, substrate release, and microbial interactions rather than as direct pathway prediction. Overall, the results provide a hypothesis-generating ecological-functional framework for explaining how microbial succession may shape the formation of alcohols, organic acids, and esters and may inform starter selection and process optimization in traditional fermented foods.