Characterization of probiotic and antioxidant properties in Saccharomyces and non-Saccharomyces yeasts isolated from Sri Lankan grape wine fermentation

Abstract

Grape skins harbor diverse microorganisms, including Saccharomyces and non-Saccharomyces yeasts, which play key roles in fermentation and enhance the sensory qualities of wine. This study aims to evaluate the probiotic and antioxidant properties of yeast strains isolated from Sri Lankan grapes, namely Hanseniaspora opuntiae J1Y-T1, Hanseniaspora uvarum JF3-T1N, Saccharomyces boulardii JSB-T2, and Starmerella bacillaris WMP4-T4. The probiotic potential was assessed by evaluating their tolerance to different levels of pH, bile salts, NaCl, phenol, and temperature, and viability under simulated gastrointestinal conditions. Antioxidant activity was assessed using ABTS and DPPH radical scavenging assays, ferric reducing antioxidant power (FRAP), and total phenolic content (TPC) assays. Accordingly, S. boulardii JSB-T2 exhibited the highest tolerance to acidic pH, bile salts, NaCl, phenol, and temperature variations. It also remained highly viable in artificial saliva, simulated gastric and intestinal juices, maintaining survival rates of 94.10% ± 1.07%, 89.89% ± 1.09%, and 85.95% ± 0.86%, respectively. All strains exhibited strong cell surface hydrophobicity and auto-aggregation, which enable colonization in the gut. Notably, S. boulardii JSB-T2 demonstrated strong antibacterial activity against foodborne pathogens and showed a moderate level of tolerance to antifungal agents compared to other strains. Antioxidant analyses revealed that all tested yeast strains possess significant antioxidant properties. In particular, S. bacillaris WMP4-T4 showed the highest antioxidant potential in the TPC and ABTS assays, while S. boulardii JSB-T2 displayed the strongest activity in the DPPH assay. Overall, the Saccharomyces strain (S. boulardii JSB-T2) demonstrated comparatively stronger probiotic characteristics than the non-Saccharomyces strains, highlighting its greater potential for functional food and pharmaceutical applications.