FIG 6.

Biofilm formation and cell motility were reduced in ALE-derived P. putida S12 strains. (A) Microtiter biofilm formation assay of P. putida S12. Plasmid-cured P. putida S12 (S12d) ΔgacS and ΔgacA showed reductions similar to those of ALE-derived P. putida S12 (S12e) strains. Restoration of the gacS locus to wild-type sequence (S12e gacS-wt) also restored biofilm formation in ALE-derived P. putida S12 (S12e). The measurement of biofilm formation was performed by measuring the optical density at 550 nm, as previously described (25), with the ΔlapA (adhesin) mutant taken as a negative control. This experiment was performed with three biological replicates, and error bars indicate standard deviations. (B) Swimming motility assay of P. putida S12 in low-viscosity agar (LB medium plus 0.3% [wt/vol] agar). ALE-derived P. putida S12 strains (S12e) showed a reduced radial growth in low-viscosity agar, indicating lower swimming motility. The Δflg mutant (flagellar gene cluster) was taken as a negative control. In the right panel, the bars represent an average of radial growth of at least three biological replicates of each strain, and error bars indicate standard deviations.