Two-component systems regulate swarming in Pseudomonas aeruginosa PA14

Swarming in Pseudomonas aeruginosa is a quorum-dependant motility over semi-solid surfaces. On soft agar, P. aeruginosa exhibits a dendritic swarm pattern, with multiple levels of branching. Swarm patterns vary considerably depending upon the experimental design. In the present study, we show that the swarm pattern is plastic and media dependent. We define several quantifiable, macroscale features of the swarm to study the plasticity observed across media. Further, through a targeted screen of 113 genes encoding two-component system (TCS) components, we show that 44 TCS genes regulate PA14 swarming in a contextual fashion. However, only four TCS genes are essential for swarming. Many swarming-defective TCS mutants are highly efficient in biofilm formation indicating an antagonistic relationship between swarming and biofilm states in P. aeruginosa.