Fig. 3: Engineered S. boulardii retain probiotic mechanisms of action in vitro.

A Schematic of probiotic mechanisms of action elicited by S. boulardii. B Percent viability after 4 h incubations of control and engineered yeast in media at pH 2.5, pH 4.0, or containing 0.3% or 0.6% OxGall bile salts (OxG). Data are shown as mean ± SD, n = 3 biological replicates. C Secretion of acetate, propionate, and butyrate from cultures of either S.b., S.b. mSA, S.b. FN, S.b. FB, and S.b. CIV, or blank media, n = 4. Solid line: simple regression of the linear portion before saturation (0 to 18 h for acetate, 0 to 12 h for butyrate and propionate. D Secretion rate of acetate, propionate, and butyrate from cultures of either S.b., S.b. mSA, S.b. FN, S.b. FB, and S.b. CIV, or blank media calculated from linear regression in (C), n = 4 biological replicates. E Concentration of murine interleukin-10 (IL-10) in the cell culture supernatant following an 18 h co-incubation of murine bone marrow-derived dendritic cells with controls (PBS or LPS 1 μg/mL) and engineered yeast, n = 3 biological replicates. F. IL-8 concentrations in HT-29 human epithelial cells co-cultured with probiotic yeast strains then stimulated with TNFa (20 mg/ml). Data are shown as mean ± SD, n = 3 biological replicates. Significance was determined using ordinary one-way ANOVA with Tukey’s for panels B, D, E, and F. For panel B, black asterisks indicate significance against S.c. For panels E, and F: black asterisks indicate significance against PBS and grey asterisks indicate significance against S.c., α = 0.05, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.