Figure 5.

Signal interference. Populations were evolved in media containing 50 μM synthetic signal (signal interference), and then assayed with and without signal addition. Signal interference led to the evolution of: (A) a lower fitness in a QS‐requiring medium that could be restored with signal, (B) a reduced level of signal gene expression that could be restored with signal, and (C) unchanged level of exoprotease production. Reduced signal expression but unchanged exoprotease production suggests that interference with the information provided by signal molecules can lead to reduced selection for signaling. Each point represents a replicate evolutionary line, the open circles represent no addition of synthetic signal and the closed circles represent cultures with addition of 50 μM synthetic signal. The dashed lines represent the means of the unevolved PAO1 wild‐type with a fully functioning QS system, and the solid lines represent a ∆lasIR mutant that does not produce or respond to synthetic signal.