Fig 2. P. aeruginosa ΔrhlI and ΔrhlR mutants have distinct colony biofilm phenotypes.

A) Pyocyanin production was measured at OD₆₉₅ in cell-free culture fluids prepared from the WT, ΔrhlR mutant, ΔrhlI mutant, ΔrhlR mutant complemented with the rhlR gene under its native promoter on pUCP18 (prhlR), and the ΔrhlI mutant supplied with exogenous 10 μM C4-HSL. Error bars represent SD for three biological replicates. B) Colony biofilm phenotypes of the strains in panel A and the ΔrhlR ΔrhlI double mutant. Again, 10 μM C4-HSL was added to the ΔrhlI mutant. Scale bar is 2 mm. C) Colony biofilm surface area quantitation for the indicated strains over 5 days. Error bars represent SEM of three independent experiments.