FIG. 3.

Comparison of WT and mutant sensitivity to oxidative stress conditions. (A) WT (AP1) and mutant (RJ1) bacteria were grown in a 5% CO₂ atmosphere until the A₆₂₀ was 0.5, and 5 mM hydrogen peroxide was added. Samples were collected at various time points, and viable counts were performed. Results are presented as the percentages of viable bacteria at a certain time point compared with the number of bacteria prior to challenge (time zero). Data points represent means of five experiments, and error bars indicate the standard deviations. (B) Growth of WT (AP1) and mutant (RJ1) in the presence or absence of paraquat. ON cultures were reinoculated in fresh THY containing 0, 2, or 10 mM paraquat. MnCl₂ or ferric citrate was added to some samples at a concentration of 30 μM. The A₆₂₀ was recorded after 15 h of incubation. Results represent the means of four experiments performed with duplicate samples. Standard deviations are indicated by the error bars.