FIG 7.

Model of Wsp and Chp pathway-mediated surface sensing modulating surface colonization and biofilm formation in P. aeruginosa. Planktonic cells can actively (via chemotaxis) or passively (environmental changes that propel bacterial cells) interact with a surface. Initial surface contact activates the Wsp and Chp signaling pathways, leading to changes in c-di-GMP and cAMP levels. Subsequently, two physiologically different subpopulations of cells arise, which differ in their c-di-GMP content. Whereas cells with elevated c-di-GMP levels increase exopolysaccharide production to initiate biofilm formation, the subpopulation with low c-di-GMP levels either detaches or explores the surface using type IV pilus-mediated motility. Detached progeny cells retain cAMP-dependent memory of the surface, and the corresponding planktonic population has an increased ability to attach to the surface.