FIG 5.

Preexposure to a low concentration of copper induces a copper tolerance response. AB5075 was subcultured at an OD₆₀₀ of 0.05 in M9 medium containing the indicated concentration of CuSO₄. After 30 min of incubation (dashed line), copper was added to a final concentration of 1.5 mM. Culture density was then measured by determining the OD₆₀₀ at the indicated time points. The data are presented as geometric means and standard errors of the means for three biologically independent experiments. For each time point, growth under each priming condition was compared by two-way ANOVA with Tukey's adjustment for multiple comparisons. Significance (P < 0.05) was found at hours 2 and 3; P values are shown in Table 2.