Figure 4.

CzcD and YiiP play a role in Zn²⁺ transport. Differential Zn²⁺-dependent pyoverdine production was estimated by relating optical densities of images acquired using UV light (<300 nm) to those acquired using white light (300–700 nm) as described in detail in the Materials and Methods section. Strains were grown for 16 h at 37°C in soft-agar plates containing Zn²⁺-loaded filter discs (5 μmoles). Bars indicate fold increase in fluorescence vs. WT. Note the increased resistance to Zn²⁺ and the increased fluorescent signal in strains czcD::dTn5 and yiiP::dTn5 vs. WT (A). Serial dilutions (10 μl) of P. aeruginosa strains initially at OD_{600 nm} = 1.0 were spotted on LB-agar supplemented with the indicated Zn²⁺ concentration (as Cl⁻) and incubated for 16 h at 37°C (B). Zinc content was determined in P. aeruginosa strains after incubation with 0.1 mM ZnCl₂ in LB medium for 2 h during early exponential phase growth. Metal contents are shown as atoms/cell (C). WT (PAO1), SM010 (pvdA mutant), DM110 (zntA and pvdA mutant), TM111 (zntA, pvdA, and czcD mutant) and TM113 (zntA, pvdA, and yiiP mutant). Data are the mean ± SE of three independent experiments. Different letters designate significantly different means as informed by a Bonferroni post hoc (p < 0.05) test of an ANOVA.