Figure 2.

Virulence phenotypes of ΔdksA1, ΔdksA2, and ΔdksA1ΔdksA2 mutants. A, growth curves of PAO1, ΔdksA1, ΔdksA2, and ΔdksA1ΔdksA2 strains in LB medium. Aliquots of bacterial cultures (n = 3) were withdrawn every hour to measure OD₆₀₀ values. B, visual comparison of bacterial culture supernatants. Loss of pigment was clearly observed in ΔdksA1 and ΔdksA1ΔdksA2 mutants. C, pyocyanin production in each strain was quantified and normalized with that of PAO1. The values of means ± S.D. (error bars) are presented (n = 3). *, p < 0.05 versus pyocyanin production in PAO1. QS−, PAO1ΔlasRΔrhlR double mutant. Pyocyanin production was also quantified in the supernatants of dksA1-complemented strains. D, relative elastase activity of tested strains. Elastase activity was measured as described under “Experimental procedures.” *, p < 0.05 versus elastase production in PAO1. E, in vivo virulence assay. The infection dose was ∼10⁸ cells/mouse. *, p < 0.05 versus survival rate of PAO1-infected mice. Five mice were used in each group.