Effect of overexpression of sigma factors on the P
expression. The sigma factors AlgU, RpoD, RpoN, RpoS and RpoF were expressed from an arabinose-inducible promoter in pHERD20T , and the P
activity was determined via β-galactosidase assay from a merodiploid strain of PAO1 carrying PmucE-lacZ integrated on the chromosome. The values reported in this figure represent an average of three independent experiments with standard error.