Essential for biofilm dispersion by sensing environmental cues. May be involved in sensing and transducing signals within cells, resulting in the modulation of c-di-GMP levels, swimming motility and adhesiveness of the bacterial cell surface. Cells are named mutant biofilms and do not disperse upon induction of the dispersion by succinate, silver nitrate, mercury chloride or sodium arsenate. They are resistant to hydrogen peroxide and more hydrophobic. They show higher intracellular levels of c-di-GMP (5- to 6-fold higher than in wild-type), increased adherent properties and impaired twitching motility. They display smaller, densely packed and symmetrical microcolonies.