Colony‐morphology screening uncovers a role for the P seudomonas aeruginosa nitrogen‐related phosphotransferase system in biofilm formation

Summary P seudomonas aeruginosa is an opportunistic human pathogen whose survival is aided by forming communities known as biofilms, in which cells are encased in a self‐produced matrix. We devised a mutant screen based on colony morphology to identify additional genes with previously unappreciated roles in biofilm formation. Our screen, which identified most known biofilm‐related genes, also uncovered PA 14_16550 and PA 14_69700 , deletions of which abrogated and augmented biofilm formation respectively. We also identified ptsP , which encodes enzyme I of the nitrogen‐regulated phosphotransferase ( PTS Ntr ) system, as being important for cyclic‐di‐ GMP production and for biofilm formation. Further experiments showed that biofilm formation is hindered in the absence of phosphotransfer through the PTS Ntr , but only in the presence of enzyme II ( PtsN ), the putative regulatory module of the PTS Ntr . These results implicate unphosphorylated PtsN as a negative regulator of biofilm formation and establish one of the first known roles of the PTS Ntr in P . aeruginosa .