Fig. 6

Mutation of hepP significantly reduced biofilm formation. Overnight growth of PA14, PA14ΔhepP, and PA14ΔzbdP was subcultured into fresh LB broth to a starting OD₆₀₀ of 0.02. Three-mL aliquots of the inoculum were dispensed into 17 mm × 100 mm polystyrene tubes and the tubes were incubated at 37 °C with gentle shaking for 24 h (a) or 48 h (b). Following incubation, the tubes were thoroughly rinsed to remove loosely attached planktonic cells and the attached cells were stained with 1% crystal violet for 1 h. The crystal violet was eluted with 95% ethanol and the eluted crystal violet, representative of the biofilm biomass, was measured at A ₅₉₅. Values represent means of 3 independent experiments ±SEM; *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; ns, no significant difference