Fig 4. The ΔhydABCDE strain of H. pylori 26695 is not attenuated for acid survival.

The wild-type (WT) strain, urease mutant strain (ΔureAB), and hydrogenase mutant strain (ΔhydABCDE) were incubated for 1 hr in PBS adjusted to pH 6.0 (A and B) or to pH 2.3 (C and D), in the absence (A and C) or presence (B and D) of 5 mM urea. The number of colony-forming units (CFU) was measured at 0 min (T₀) and at 60 min (T₆₀), and percent survival was calculated as CFU at T₆₀ divided by CFU at T₀. Data from individual biological replicates are shown as points, with the bar plotted at the mean. Open symbols indicate that no bacteria were recovered and thus, the CFU are plotted as a function of the limit of detection (1000 CFU/mL). Three biological replicates were performed. For panels A-C, a one-way ANOVA followed by Dunnett’s test for multiple comparisons was performed; the comparison was made only to WT. In panel D, the same statistical tests were performed on the log-transformed data. **** = p < 0.0001.