Unique genetic basis of the distinct antibiotic potency of high acetic acid production in the probiotic yeast Saccharomyces cerevisiae var. boulardii

RHA for identification of the causative gene in QTL2. (A) Overview of QTL2 dissection to nucleotide level resolution. Division of QTL2 into nine gene blocks for bRHA and genes present in block 8. (B) Acetic acid accumulation by the bRHA strains for block 8 and for WHI2. The bRHA strains for block 8 or WHI2 are shown as SB Block8Δ or SB whi2Δ and Sc Block8Δ or Sc whi2Δ for reciprocal deletions in the SBERH6 and S288c genome, respectively, in the SBERH6/S288c sdh1^H202Y,F317Y background. Strains: SBERH6/S288c sdh1^H202Y,F317Y (□), SBERH6/S288c sdh1^H202Y,F317Y B8Δ (▴), SBERH6 B8Δ/S288c sdh1^H202Y,F317Y (▾), SBERH6 whi2Δ/S288c sdh1^H202Y,F317Y (▿), and SBERH6/S288c sdh1^H202Y,F317Y whi2Δ (▵). (C) Acetic acid accumulation by SBERH6 strains with modifications of WHI2. Strains: SBERH6 (○), SBERH6 whi2Δ (▴), SBERH6 WHI2-FL (WHI2^*287S) (▪), and SBERH6 WHI2^Sc (S288c allele of WHI2) (▾). (D) Acetic acid accumulation by Sb.P with its two copies of whi2^S287* replaced by two copies of WHI2^Sc. Strains: Sb.P (•), Sb.P WHI2^Sc/WHI2^Sc (▪), and Sb.P whi2^287* reintegrant (○). Results are the means of three biological replicates for each time-point. Error bars show standard deviation at each time-point. (E) Spot growth assays on solid YPD (2%), YPAc (0.5%, pH 5), and YPAc (1%, pH 5) agar medium at 30°C and 37°C for S288c, Sb.P, and Sb.P WHI2^Sc/WHI2^Sc. Gradient dark color on wedge indicates cell culture dilution strength prior to spotting.