Comparative Microbiome and Functional Profiling of Cowpea Kimchi Fermented Using Korean and Sichuan Techniques

Fermented vegetables host complex microbiomes that drive flavor and functionality. We compared cowpea pod fermentations produced by a Korean kimchi-style method (HG) versus a Sichuan paocai-style method (SC) to isolate technique-driven effects on community structure and functional potential. Cowpea pods were fermented for 10 days in triplicate, profiled by 16S rRNA (V3-V4) amplicon sequencing, analyzed in QIIME2, and functionally inferred with PICRUSt2. SC exhibited higher alpha diversity (Shannon, Chao1, Simpson) than HG (p < 0.05), and beta-diversity (Bray-Curtis dissimilarity) showed clear separation by fermentation style (PERMANOVA p = 0.001), indicating method-dependent community assembly. Both styles were dominated by lactic acid bacteria, chiefly Leuconostoc, Lactobacillus, and Weissella, but their proportions differed: HG retained higher Leuconostoc/Weissella, whereas SC favored Lactobacillus. Predicted functions diverged accordingly: HG was enriched for carbohydrate-metabolism genes (e.g., β-galactosidase; dextransucrase), consistent with rapid sugar fermentation and possible exopolysaccharide formation; SC showed enrichment of amino-acid-related pathways (e.g., acetolactate synthase; glutamate dehydrogenase), heterolactic fermentation, and γ-aminobutyric acid (GABA) biosynthesis, suggesting broader metabolic outputs relevant to flavor development and potential health attributes. Overall, fermentation technique substantially shapes both the microbiome and its predicted repertoire, with HG prioritizing carbohydrate catabolism and SC showing expanded metabolic potential; these insights can inform starter selection and process control for targeted product qualities.