Las-like quorum-sensing system negatively regulates both pyoluteorin and phenazine-1-carboxylic acid production in Pseudomonas sp. M18

A las-like quorum-sensing system in Pseudomonas sp. M18 was identified, which consisted of lasI and lasR genes encoding LuxI-LuxR type regulator. Several functions of the las system from strain M18 were investigated in this study. The chromosomal inactivation of either lasI or lasR by recombination increased the production of both pyoluteorin (Plt) and phenazine-1-carboxylic acid (PCA) by 4–5 fold and 2–3 fold over that of the wild type strain of M18, respectively. Production of both antibiotics was restored to wild-type levels after in trans complementation with the wild-type lasI or lasR gene. Expression of the translational fusions pltA′-′lacZ and phzA′-′lacZ further confirmed the negative effect of lasI or lasR on both biosynthetic operons, and it was also demonstrated that the las system was related to the ability of swarming motility and the inhibition of cell growth. Supported by the Science Program of the China National 10th “Five-year Plan” (Grant No. 2004BAAA308A21-6), the National Natural Science Foundation of China (Grant No. 3037004), the National High Technology Research and Development Program (863 Program) of China (Grant No. 2007AA02Z215), New Century Excellent Talent Program (NCET) in China and Shanghai Leading Academic Discipline (Project Number: B203)