FIGURE 4.

Growth of AB4857 and AB5711 carrying Region D. Region D from AB5075 was cloned into pAJ100 and transformed into AB4857 and AB5711, which do not naturally encode the region D genes. Strains carrying the empty vector, pAJ100, were used as controls. The strain background is indicated in the graph title (AB4857, left; AB5711, right); strains carrying the control vector pAJ100 are indicated with dotted lines, and strains carrying pAJ100-Region D are indicated with solid lines. Strains were grown for 6 h at 37°C in M9 medium supplemented with the indicated concentration of CuSO₄. Growth was measured both by turbidity (OD₆₀₀, data not shown) and enumeration of viable colonies (CFU/mL). The data are presented as geometric mean and SEM of three biologically independent experiments. Two-way ANOVA with Tukey’s adjustment for multiple comparisons was used to compare growth of the strain carrying the pAJ100 vector to the strain carrying pAJ100-Region D in each copper concentration at each timepoint. The symbols indicate how many comparisons were statistically significant (P < 0.05) at each timepoint, as follows: ∼, growth in 1.5 mM CuSO₄ was different between the two strains; +, growth in 1 and 1.5 mM CuSO₄ was different between the two strains *, growth in 0.5, 1, and 1.5 mM CuSO₄ was different between the two strains.