Figure 3.

Effect of weak acids and bases on growth phenotypes. Growth measurements of isogenic wild-type (WT, ▪) or nha1Δ (•), nhx1Δ (□) and nhx1Δ nha1Δ (○) mutants grown for 18 h at 30°C in APG medium adjusted as follows. (A) pH 4.0 in the presence of increasing concentrations of acetic acid. (B) pH 2.7 in the presence of increasing concentrations of the weak base chloroquine. (C) pH 4.0 in the presence of 10 μg/ml Hygromycin B and increasing concentrations of the weak base TMA. (D) pH 4.0 in the presence of 600 mM KCl and increasing concentrations of TMA. Note that growth of mutants in APG pH 4.0 in the absence of weak acid was indistinguishable from wild-type. Mean values normalized to control and calculated SEs are plotted from at least three independent experiments.