Fig 6. Urease activity of H. pylori B128 wild type strain, isogenic mutants and complemented strains.

Strains were grown in Brucella β-cyclodextrin medium without added nickel (grey bars) or with 10 µM nickel (black bars). The identity of each strain is indicated below the bars. Urease activity is expressed as μmol of urea hydrolyzed. min^-1. mg^-1 of protein. The data correspond to the mean value of three independent experiments with at least triplicate tests for each strain. Error bars represent the standard deviation. *** indicates that the mean value is significantly different from that of the wild type strain (P < 0.01).