FIG 4 .

Swarming motility of strains PAO1 (A) and PA14 (B) and mutants derived from the two strains. Plates were inoculated as described in Materials and Methods. The diameters of the motility areas of 10 different colonies per strain were measured. Each symbol represents the value for one colony, and the mean value for the 10 colonies is indicated by the short black bar. The values (means) that are significantly different (P < 0.0001 by Student’s t test) from the mean value for the wild-type strain are shown by a bar and asterisk. The rest of the single and double ampD mutants of both PAO1 and PA14 showed wild-type swarming motility levels (not shown). The pictures above the graph show representative images of the corresponding strains.