FIG 3 .

Sessile growth assay for observing the effects of mutations in genes of the σ²² stimulon on the activation of the σ²²-dependent promoter, PalgD. Shown are pictures of plates of L agar plus chloramphenicol (Cm) coated with mutant derivatives of PAO1 that hosted pLW117, a plasmid containing PalgD-cat, which confers Cm^r and thus growth when activated. A 5-mm filter disk impregnated with d-cycloserine was placed in the center of the plate. With PAO1, exposure to d-cycloserine (10 µg) in the center of the plate produced a ring of Cm^r growth after 3 days at 25°C. A mucA mutant (devoid of the σ²² anti-sigma factor) is shown as an example of σ²² derepression. The other plates show a lawn of growth with the mutants indicated, which occurred with or without d-cycloserine and indicated constitutive activation of PalgD-cat due to the mutation.