(A) Ethanol titers from glucose fermentation (top) of one laboratory (S288C) and three industrial (PE-2, Ethanol Red, Kyokai 7) yeast strains, or from xylose fermentation (bottom) of an engineered xylose strain, in unmodified YSC or YSC supplemented with 40 mM KCl and 10 mM KOH. (B) Titers from S288C cultured in 20% yeast extract-peptone medium (YP) or that supplemented with potassium, at pH 6 and 3.7. (C) Population fractions of S288C after transfer from overnight growth in unmodified YSC (dashed), or that supplemented with 48 mM KCl and 2 mM KOH (solid), into media containing the indicated concentrations of ethanol. (D, E) Same as C, but with step increases of isopropanol or isobutanol, respectively. All data are mean ± SD from 3 biological replicates.