Fig. 3: The cadD locus is implicated in zinc stress response and survival of zinc toxicity.

A Analysis of wild-type parental GBS strain harboring the empty shuttle vector (WT:EV, pink circles), an isogenic ΔcadD mutant harboring the empty shuttle vector (ΔcadD:EV, purple squares), and complemented derivative (ΔcadD:C, blue triangles) final absorbance as determined by spectrophotometric determination of optical density at 600 nm (OD₆₀₀) at 24 h post-inoculation in increasing concentrations of zinc (1 mM and 2.5 mM). B Analysis of bacterial viability (Log CFU/mL) in medium alone or supplemented with zinc (1 mM, 2.5 mM, or 5 mM). Bacterial cultures were grown overnight and subjected to serial dilution and plating for quantitative culture analyses. C Elemental analyses by ICP-MS of the WT (pink bars), isogenic cadD mutant (purple bars), or complemented derivative (blue bars) when grown in media supplemented with 100 µM zinc. D Real-time RT-PCR analyses of cadD expression in response to exposure to 0.5 mM zinc (pink bar) or 1 mM zinc (purple bar) compared to cells grown in medium alone (black bar). Bars indicate the mean of three independent biological replicates +/− SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, one-way ANOVA with Dunnet’s post hoc multiple corrections test compared to WT or medium alone controls. Individual data points indicate separate biological replicates.