FIG. 4.

Sensitivities of CFT073, CFT073cueO, and CFT073cueO(pCueO) to H₂O₂. Approximately 1 × 10⁶ cells for each strain were harvested in mid-exponential growth phase and incubated for 1 h in the presence of 0, 2.5, 5.0, and 7.5 mM H₂O₂. The reaction was stopped by serial dilution of cells into PBS containing 1,000 U/ml catalase. The number of viable cells remaining after H₂O₂ treatment was determined by direct colony counts. Error bars represent the standard errors from the results for triplicate assays.