Figure 1

Effect of subinhibitory concentration of tobramycin on swarming motility in P. aeruginosa PUPa3. a) Swarming of P. aeruginosa PUPa3 on 0.5% LB agar plates at 37°C after 24 hrs. WT swarms (A), but in presence of SIC of tobramycin (0.05 μg/mL) cannot swarm (B). Swarming was not present in the rhlI mutant (C) nor in double mutant lasI/rhlI (D). b) Swarming of P. aeruginosa PUPa3 on 0.5% LB agar plates at 37°C after 40 hrs. Normal swarming occurs in WT (A), no swarming is present in WT on plate supplemented with SIC of tobramycin (B) and swarming was restored upon the addition of 2 μM exogenous synthetic C4-HSL (C). Swarming in the rhlI mutant was also restored upon the addition of 2 μM exogenous synthetic C4-HSL (D), but not upon the addition of 2 μM exogenous synthetic 3-oxo-C12-HSL (E).