FIG. 7.

Effect of ankB, katB, and katB ankB on sensitivity to H₂O₂. All bacteria were grown aerobically overnight in M9F medium at 37°C. Fresh prewarmed medium (1 volume of culture in 10-volume flasks) was inoculated with 1/50 of the final culture volume and allowed to reach an OD₆₀₀ of 0.6. Some bacteria were pretreated with a sublethal (1 mM) dose of H₂O₂ for 1 h (shaded bars) relative to control bacteria (open bars). The suspensions were diluted 100-fold in 7 ml of M9F 0.6% top agarose kept at 37°C and poured onto M9F plates. Filter paper disks (7 mm) impregnated with 8.8 M H₂O₂ were placed on the top agar surface. Zones of growth inhibition were measured after a 24-h aerobic incubation at 37°C. Bars: 1, PAO1; 2, ankB; 3, katB; 4, katB ankB; 5, ankB plus pUCP22; 6, ankB plus pankB; 7, katB ankB plus pUCP22; 8, katB ankB plus pankB. Error bars indicate standard errors of the means.