FIG. 6.

Effect of zinc on bacterial growth and biofilm production. (A) Biofilm. Zinc sulfate (black bars), calcium chloride (hatched bars), and magnesium chloride (white bars) were added at the indicated concentrations to TSB containing a fixed concentration of NTZ (12.5 μg/ml; gray bars). Zinc chloride, but not the other metals, reversed the biofilm-inhibitory effect of NTZ, with 50% reversal occurring at ∼5 μM. (B) Growth. Effect of the following metals or conditions on bacterial growth at a fixed concentration of NTZ (12.5 μg/ml): ZnSO₄ (black bars), ZnCl₂ (dark gray bars), no metal (light gray bar), DMSO control (white bar), and no NTZ (dark gray bar).