The aim of the present study was to study the properties and the effects of pyocyanin produced by carbencillin resistant mutants of Pseudomonas aeruginosa against some gram negative and gram positive strains. Three groups of Carbencillin resistant mutants of P. aeruginosa were isolated. Group III of mutants' posses the ability of producing pyocin S. The ability of these mutants to produce pyocyanin was investigated; both mutant groups I and II were found to produce more pyocyanin whereas group III lost its ability to produce pyocyanin. The antibacterial activity of pyocyanin produced by mutants was tested against some gram negative strains (Escherisia coli, Proteus mirabilis), gram positive strain (Staphylococcus aureus), Candida albicans and C. tropicalis; the result showed that the antibacterial activity was increased .The mutants groups also showed different ranges of antibacterial activity as determined by their MICs. Group I was more effective against gram negative strains, Candida albicans and C. tropicalis than wild type Ps7 while group II was more effective against gram positive strains than wild type Ps7.
Key words: Pseudomonas aeruginosa, pyocyanin, Carbencillin resistant, mutant
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