Defects in attachment and biofilm formation in the typA mutant. (A) Requirement for typA in rapid attachment. Attachment was determined using diluted overnight cultures for 60 min at 37°C. Adhered cells were stained with crystal violet. (B) Requirement for typA in static biofilm formation. Cells were grown for 24 h at 37°C in polystyrene microtiter plates containing BM2 medium with 0.5% (w/v) casamino acids. Microtiter wells were washed several times during incubation to remove planktonic bacteria. Adherent biofilms were stained with crystal violet, followed by ethanol solubilization of the crystal violet and quantification (A595nm) of stained wells. The box plots (median, thick line in the box) represent the mean of 3 independent biological repeats, each assayed in quintuplicate (n = 15). *** indicates a statistically significant difference (p < 0.001), between the typA mutant and PA14 WT as determined by Whitney Mann test.