Fig. 2.

Pellicle biofilm formation of ATCC 17978 wildtype and mutants (a) and 29D2 wildtype and mutants (b). A. baumannii pellicle biofilms developed within 3 days of incubation at room temperature were stained with a 0.5% crystal violet solution for 20 min. The biofilm was scrubbed and flushed off the tube walls and absorption determined at 550 nm. For each strain three independent experiments were performed and statistical significance was analyzed by the Student’s t test (two-tailed, unpaired). Significance as indicated: *P value ≤ 0.05; **P value ≤ 0.01; ***P value ≤ 0.001; ****, P value ≤ 0.0001