FIG 5 .

The Δmua mutant is more resistant to acid challenge than the WT is. WT H. pylori strain 26695 and its Δmua isogenic mutant were grown on unsupplemented BA medium or BA supplemented with 50 µM NiCl₂. Cells were harvested, resuspended in BHI at pH 7.4, pH 4.5, or pH 2.5 with 10 mM urea, and left for 60 min before being serially diluted, spread on plates, and counted a few days later. Results shown are the averages and standard deviations of three independent growth and acid challenge experiments. Asterisks indicate a significant difference between the Δmua mutant and the WT strain (*, P < 0.005; **, P < 0.05 [determined by Student’s t test]).