FIG. 3.

Effects of pH and dimethyl glyoxime on urease activities. Urease activities of strains grown in BHI medium with 5% fetal bovine serum at pH 7.3 (white) or pH 5 (black) or with the nickel chelator dimethyl glyoxime at pH 7.3 (gray) are shown. The results shown are means and standard deviations of six replicate samples; these six replicates are from two independent cultures, each sampled three times. The entire experiment was performed two additional times (again with two cultures for each experiment), with results similar to those shown. At pH 5, the urease activities of the wild type (WT) are significantly higher (P < 0.05) than at pH 7.3, and the chelator-added condition was not different from that without chelator (pH 7.3). The activities of the chelator-added condition for the mutants are significantly lower than without chelator (P < 0.01).