Effects of Arr Mutation on Biofilm and Pyocyanin Biosynthesis in Pseudomonas aeruginosa

Abstract:

As an opportunistic pathogen, Pseudomonas aeruginosa can produce biofilm and pyocyanin, which play a critical role in its pathogenesis. This study aims to elucidate the function of the Arr gene in formation of biofilm and production of pyocyanin in Pseudomonas aeruginosa. Using the chromosome DNA of Pseudomonas aeruginosa as template, we first cloned the Arr gene by PCR. With the insertion of gentamycin resistance cassette (aacC1), the mutant PA-AG has then been constructed by homologous recombination. The formation of biofilm is determined by staining with crystal violet, and production of pyocyanin is detected with spectrophotometric method. In KMB or LB medium, biofilm formation of the parental strain PAO1 is about 2 folds higher than that of the Arr mutant PA-AG. The biosynthesis of pyocyanin in the Arr mutant PA-AG is about 2.5 folds higher than that in the parental strain PAO1. These results indicate that the Arr gene negatively controls the pyocyanin biosynthesis, but Arr could exert some positive effect on the biofilm formation. It is suggested that regulation mediated by the Arr gene on biofilm and biosynthesis of pyocyanin in Pseudomonas aeruginosa is specific and different.