Synthesis of N-acyl homoserine lactones and phenazines, some enzymatic activities, and fungicidal activity in the cells of Pseudomonas chlororaphis 449 with inactivated rpoS gene

Abstract

The inactivation of the rpoS gene, which encodes the sigma S subunit of RNA polymerase of rhizospheric strain Pseudomonas chlororaphis 449 results in a drastic (5–8-fold) decrease in the synthesis of phenazine antibiotics, a decline in the acid and alkaline phosphatase activities (pH 2.5 and 8.8, respectively), and the antagonistic activity of this strain against phytopathogenic fungus Rhizoctonia solani. A mutation in the rpoS gene also causes a minor decrease of lipase and proteolytic activity in the supernatants of Pseudomonas chlororaphis 449 and has no substantial effect on the synthesis of three types of N-acyl homoserine lactones, the signal molecules of quarum sensing regulation, and the ability of bacteria to migrate over the medium surface (swarming).