The Prebiotic Potential of Porphyra-Derived Polysaccharides and Their Utilization by Lactic Acid Bacteria Fermentation

Abstract

Porphyra-derived polysaccharides (PPs) are promising prebiotic candidates due to their capacity to modulate gut microbiota and promote host health. However, their interactions with and utilization by probiotic microorganisms remain unclear. In this study, the fermentability of PPs by murine-derived lactic acid bacteria (LAB) strains was investigated, with particular attention to strain-specific metabolic activity, carbohydrate utilization, and potential exopolysaccharide (EPS) production. All tested strains were capable of utilizing PPs to varying extents, with strain A10 exhibiting the highest level of carbohydrate consumption. Notably, strain A5 showed increased mannose concentrations following fermentation, suggesting the biosynthesis of mannose-rich EPSs. HPLC analysis confirmed the presence of high-molecular-weight polysaccharides ranging from 2.6 to 8.1 x 105 Da, indicative of EPS production. FT-IR spectroscopy further revealed spectral features consistent with EPS structures. The antibacterial activity of postbiotic compounds produced by LAB strains fermenting PPs against Escherichia coli and Staphylococcus aureus was observed. These findings demonstrate distinct metabolic adaptations of LAB strains to PPs and emphasize their potential as prebiotic substrates.