Transcriptome-wide differences between Saccharomyces cerevisiae and Saccharomyces cerevisiae var. boulardii: Clues on host survival and probiotic activity based on promoter sequence variability.

Although Saccharomyces cerevisiae and S. cerevisiae var. boulardii share more than 95% genome sequence homology, only S. cerevisiae var. boulardii displays probiotic activity. In this study, the transcriptomic differences exhibited by S. cerevisiae and S. cerevisiae var. boulardii in intestinal like medium were evaluated. S. cerevisiae was found to display stress response overexpression, consistent with higher ability of S. cerevisiae var. boulardii to survive within the human host, while S. cerevisiae var. boulardii exhibited transcriptional patterns associated with probiotic activity, suggesting increased acetate biosynthesis. Resorting to the creation of a S. cerevisiae var. boulardii genomic database within Yeastract+, a possible correlation between loss or gain of transcription factor binding sites in S. cerevisiae var. boulardii promoters and the transcriptomic pattern is discussed. This study suggests that S. cerevisiae var. boulardii probiotic activity, when compared to S. cerevisiae, relies, at least partially, on differential expression regulation, based on promoter variability.