Construction And Characterization Of A PpbR Gene Mutant Of Pseudomonas Sp. M18

Pseudomonas sp. M18, one of the plant-growth-promoting rhizobacteria can produce secondary metabolites including phenazine-1-carboxylic acid (PCA) and pyoluteorin (Plt). Here we describe the new regulator gene named ppbR (positive PCA biosynthesis regulator) in Pseudomonas sp. M18. According to sequence analysis, it was discovered that the ppbR fragment in M18 had 99.63% similarity to the PA2572 ORF DNA sequence from P. aeruginosa PAO1. PpbR contains two predicted domains: a putative response regulator CheY-like domain and a HD-GYP domain based on bioinformatics analysis. In order to investigate ppbR genetic function, we constructed the chromosomal ppbR disrupted mutant M18P. Results show that the M18P has less flagellar swimming and swarming motility. It also yields fewer PCA in both KMB and PPM medium. However there is no remarkable difference in the ability to produce pyoluteorin as compared with the wild type M18. In PPM medium, the production of PCA was only 50% of the wild type. The positive regulation of ppbR on PCA biosynthesis was further...