Antioxidant properties and global metabolite screening ofthe probiotic yeast Saccharomyces cerevisiae var. boulardii

BACKGROUND: Saccharomyces cerevisiae var. boulardii is the only yeast species with probiotic properties. It is considered to have therapeutic significance in gastro-intestinal disorders. In this paper, a comparative physiological study between this yeast and Saccharomyces cerevisiae (BY4742) was performed by evaluating two prominent traits of probiotic species, responses to different stress conditions and antioxidant capacity. A global metabolite profile was also developed in order to identify which therapeutically important secondary metabolites are produced. RESULTS: S. cerevisiae var. boulardii showed no significant difference in growth patterns but greater stress tolerance when compared with S. cerevisiae. It also demonstrated a 6-10-fold greater antioxidant potential (judged by the DPPH assay), with 70-fold higher total phenolic content and 20-fold higher total flavonoid content in the extracellular fraction. These features were clearly differentiated by principal component analysis and further elucidated by metabolite profiling. The extracellular fraction of the S. cerevisiae var. boulardii cultures was found to be rich in polyphenolic metabolites viz. vanillic acid, cinnamic acid, phenyl ethyl alcohol (rose oil), erythromycin, amphetamine and vitamin B6 which results in the antioxidant capacity of this strain. CONCLUSION: This study presents a new perspective of differentiating the two genetically related strains of yeast, Saccharomyces cerevisiae and Saccharomyces cerevisiae var. boulardii by assessing their metabolome fingerprints. In addition to the correlation of the phenotypic properties with the secretory metabolites of these two yeasts, the work also emphasizes the potential to exploit S. cerevisiae var. boulardii in the industrial production of these metabolites.