FIG 5.

The effect of copper on biofilm formation and expression of genes regulated by CpxR in the wild-type P. mirabilis, mutants, and respective complemented strains. (A) Biofilm formation. The bacterial strains used were the same as in Fig. 1. The diluted overnight bacterial cultures were inoculated into the LB-containing microtiter wells with or without copper (1 mM). The OD₆₀₀ of each well was obtained after overnight incubation, and the biofilm formation ability was determined as described in Fig. 1. nil, no-copper control. (B) Expression of genes regulated by CpxR. The bacterial strains used were the same as those in Fig. 3A. The promoter activity was determined as described in Fig. 2C in the presence and absence of copper (1 mM). Only results after incubation for 24 h were shown. The data are averages and standard deviations of the results from three independent experiments. (A and B) Significant differences were determined by using two-way ANOVA with Tukey’s multiple-comparison test (*, P < 0.05; **, P < 0.01).