Lactiplantibacillus plantarum Fermentation Enhances the Bioactivity of Polymeric Proanthocyanidins: Gut Microbiota Regulation via Caffeic Acid Production

Polymeric proanthocyanidins (PPC) typically exhibit low bioavailability. While probiotic metabolism can enhance polyphenol bioactivity, the interaction between Lactiplantibacillus plantarum and PPC remains underexplored. In this study, L. plantarum SFFI23, a strain exhibiting excellent capacity to metabolize PPC, was selectively isolated. During in vitro digestion and fecal fermentation, SFFI23 reduced the degree of polymerization of PPC and enhanced overall antioxidant capacity. Metagenomic analysis revealed that SFFI23-PPC metabolism resulted in Firmicutes enrichment, accompanied by opportunistic pathogen reduction and an upregulation of health-associated pathways such as quorum sensing. Metabolomics analysis showed significant enrichment in 17 metabolic pathways. Multiomics analyses revealed that caffeic acid, derived from SFFI23-PPC metabolism, contributes to improved gut health by regulating gut microbiota and promoting metabolic reprogramming. This study outlines a triadic mechanism: "biotransformation by L. plantarum-metabolic activation of PPC-gut microbiota regulation", highlighting the potential of SFFI23 as an adjunct for enhancing PPC bioactivity.