FIG 1.

Biofilm formation of wild-type P. mirabilis, mutants, and respective complemented strains. The OD₆₀₀ of LB overnight bacterial cultures in each microtiter was determined, and the biofilms were stained with crystal violet (1%). The OD₅₇₀s of the extracts from the crystal violet-stained biofilms by acetone and alcohol were determined to calculate the OD₅₇₀/OD₆₀₀, representing the ability of biofilm formation. The data are the averages and standard deviations of the results from three independent experiments. Significant differences were determined by using a one-way analysis of variance (ANOVA) with Tukey’s multiple-comparison test (*, P < 0.05; **, P < 0.01; ***, P < 0.001). wt, wild type; zapD, zapD mutant; zapDc, zapD-complemented strain; cpxR, cpxR mutant; cpxRc, cpxR-complemented strain; zapD-pcpxR, zapD mutant with the cpxR-expressing plasmid; cpxR-pzapBCD, cpxR mutant with the zapBCD-expressing plasmid; zapA, zapA mutant; zapAc, zapA-complemented strain.