Functional and genomic evaluation of novel exopolysaccharide produced by marine Pediococcus pentosaceus E3 with...

Lactic acid bacteria (LAB) exopolysaccharides (EPS) are highly valuable due to their unique structure and functional properties. Pediococcus pentosaceus E3 is a promising marine probiotic strain. An investigation of the E3 genome identified a gene cluster responsible for EPS production, comprising 13 genes organized into four regions: the regulatory region for EPS expression, the chain length determination region, genes that catalyze the biosynthesis of EPS repeat units, and genes for polymerization and EPS transportation. Furthermore, a total of 16 key enzymes involved in the nucleotide sugar biosynthesis pathway were predicted according to the KEGG metabolic pathways in the E3 genome sequence. Therefore, the current study investigates the characteristics and bioactivities of E3-EPS. E3 strain was grown in MRS broth supplied with 1.0% sucrose for EPS production, and E3 produced a significant quantity of EPS (400 mg/L). Structural characteristics of E3-EPS were investigated through carbohydrate content determination, FTIR, SEM, EDX, TGA, HPLC, and NMR. HPLC analysis revealed that E3-EPS is a heteropolysaccharide composed of four sugar moieties: galactose, glucose, mannose, and fucose. Moreover, E3-EPS demonstrated promising bioactivities, as its anticancer activity was evaluated against colon cancer cell lines, and the IC₅₀ value was determined to be 77.05 ± 0.24 µg/mL. E3-EPS inhibited α-amylase activity by 58.3% and 82.8% at 10 and 100 µg/mL concentrations, respectively. Additionally, E3-EPS successfully decreases the expression levels of inflammatory cytokines (TNF-α and IL-6). The findings of this study suggest that the safe marine probiotic P. pentosaceus E3 is a source of unique EPS suitable for pharmacological applications.