| Pseudomonas aeruginosa is an opportunistic pathogen causing chronic lung infections in cystic fibrosis patients and immunocompromised individuals and a major source of nosocomial infections[1]. P. aeruginosa is considered as serious pathogen because of its bearing innate multiple drug resistance and having a set of virulent factors, eg. alkaline protease, phenazines,toxins and so on.Pyocynin is a derivative of phenazine compound and not only act as virulent factor but also a signal molecule in P. aeruginosa. It is important to understand the virulence mechanism and the regulatory pathways of phenazine synthesis.In this study we investigated the regulation of phenazine biothesis by random inserting a transposon into P. aeruginosa genome and subsequently selecting mutants affecting phzA1 expression. Six mutants were identified and the transposon inserting site of the transposon in these mutants was determined by semi-random PCR method and the genes disrupted were determined by using BLAST software. Some of the genes identified are unknown genes. The results provide new information in the regulation of virulent factors in P. aeruginosa.Meanwhile, a mutant with colony and culture color being apparently different from those of wild-type was investigated further. The results indicate that the mutated gene is PA1196 which encodes a novel transcriptional regulator. Using gene replacement method its function as phzA1 regulator was verified.Gene knockout mutants of PA0602 and PA4594 genes were also constructed, and both of the genes code a component of ATP-binding cassette (ABC) transport. And the relationship between these two genes and QS as well as PQS systems was investigated.
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