Evaluation of Saccharomyces cerevisiae Yeast Cell Wall as a Microbial-Derived Prebiotic Substrate for Enhancing the Functional Properties of Lactic Acid Bacteria

Abstract Saccharomyces cerevisiae yeast cell wall (SC), a fermentation by-product rich in β-glucans, mannans, and mannoproteins, was evaluated as a sustainable microbial-derived prebiotic for Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus, and Levilactobacillus brevis. FTIR confirmed the characteristic structure of SC. Its effects on probiotic functionality were assessed through growth kinetics, biomass production, antimicrobial, antioxidant, enzymatic, and organic acid analyses, using MRS and inulin as controls. SC significantly enhanced biomass production, with the highest yield obtained for L. paracasei in 10% SC (5.85 g), compared with 3.75 g in MRS. L. rhamnosus showed superior antimicrobial activity in SC supplemented medium and inhibited Escherichia coli and Staphylococcus aureus (up to 4 mm), while L. paracasei exhibited 76.06% DPPH scavenging activity. L. rhamnosus showed the highest lipase (5.80 U/mL) and lactic acid (11.80 g/L) production, whereas L. brevis produced the highest acetic (0.56 g/L) and butyric acids (0.0050 g/L). These findings demonstrated that SC is a promising sustainable microbial-derived prebiotic for synbiotic fermentation and valorization of industrial yeast by-products.