Pyocyanin,an important virulence factor,is synthesized and secreted by Pseudomonas aeruginosa PAO1 and plays a critical role in pathogen-host interaction during infection.Sigma~(38)(σ~(38),σ~S) is a central regulator for many virulence production in pathogens.[Objective] Our aim is to identify expression and regulation of two phenazine-producing operons mediated by the sigma~(38) factor in Pseudomonas aeruginosa PAO1.[Methods] We first cloned the flanking fragments of rpo S from the chromosomal DNA of P.aer...