FIG 4 .

Insertional inactivation of the mua and/or nikR gene(s) renders H. pylori Ni sensitive. WT H. pylori strain 26695 and its Δmua, ΔnikR, and Δmua ΔnikR isogenic mutants were grown in BHI with the indicated supplemental NiCl₂ concentrations. Growth yield was monitored by measuring the OD₆₀₀ 24 h after inoculation and is expressed as a percentage of the OD₆₀₀ of the WT strain in unsupplemented medium (set at 100%; no error bar). Black bars represent WT H. pylori 26695, white bars the Δmua mutant, dark grey bars the ΔnikR mutant, and light grey bars the Δmua ΔnikR double mutant strain. Results shown are the averages and standard deviations of three independent growth experiments. Asterisks indicate a significant difference in growth yield between each mutant and the WT (P < 0.01 for 0.25, 0.5, and 0.75 mM NiCl₂; P < 0.02 for 1 mM NiCl₂ [determined by Student’s t test]).