Figure 3

β-Galactosidase activity assays of P _vapA -acZ virS and virR deletion mutant strains. β-Galactosidase activity (measured in Miller units) of the wild-type strain (TKR255), ΔvirS, pINT::P _aphII -virS-integrated ΔvirS (P _aphII -virS/ΔvirS), pINT::P _aphII -virS (D57A)-integrated ΔvirS [P _aphII -virS (D57A)/ΔvirS], virR _ΔHTH , pINT::P _virR -virR-integrated virR _ΔHTH (P _virR -virR/virR _ΔHTH ), and pINT::P _aphII -virS-integrated virR _ΔHTH (P _aphII -virS/virR _ΔHTH ) strains grown at pH 6.5 (lanes 1 and 3) or pH 8.0 (lanes 2 and 4). Error bars represent standard deviations for each data set (n = 3). Data were evaluated for statistical significance using one-way ANOVA followed by the Dunnett s multiple comparison test, *p < 0.001.