Objective: As an opportunistic pathogen, Pseudomonas aeruginosa PAO1 can produce phenazine and its derivatives, which play a critical role in their pathogenesis. In many bacteria, RpoS, the product of rpoS gene, mediates biosynthesis of a set of secondary metabolites.
Objective: This study aims to elucidate rpoS gene's function and regulation on two phenazine gene clusters in Pseudomonas aeruginosa PAO1.
Methods: The rpoS gene and its upstream and downstream fragments were cloned from the chromosome of Pseudomonas aeruginosa. With the insertion of gentamycin resistance cassette (aacC1), the mutant PA-SG has been created by homologous recombination. Translational fusion plasmids phz1'-'lacZ (pMEZ1) and phz2'-'lacZ (pMEZ2) were constructed, and then were introduced into the wild type strain PAO1 and the mutant PA-SG, respectively. Activities of beta-galactosidase in them were determined with Miller method.
Results: In KMB or PPM medium, beta-galactosidase activity of phzl'-'lacZ in the mutant PA-SG is much more than that in the wild type strain. However, beta-galactosidase activity of phz2'-'lacZ in the wild type strain is 2 -3 folds more than that in the mutant PA-SG.
Conclusion: With these results, it is suggested that regulation mediated by rpoS gene on two phenazine loci is specific and different.