FIG. 7.

Relative amounts of biofilm formation in the wild-type, Δppk1, and Δppk1c strains. Static biofilm formation in borosilicate tubes was assessed by inoculating 100 μl of culture with an OD₆₀₀ of 0.05 into 1 ml of MH broth and incubating it at 42°C under microaerophilic conditions for 2 days without shaking. Biofilms were visualized by staining with 250 μl of 1% crystal violet for 15 min. Biofilms were quantified by measuring the absorbance at 570 nm after dissolving them in 1 ml of dimethyl sulfoxide for 24 to 48 h. Each bar represents the mean ± SE of two independent experiments. *, P < 0.01. WT, wild type.