Aerotactic responses by wild-type and mutant strains of P. aeruginosa. Changes in the green fluorescent protein (GFP) fluorescence intensity of the upper well were measured by a fluorescence spectrophotometer. Symbols: ○, PAO1(pMRP9-1) (wild type); ▵, TLPC01(pMRP9-1) (aer mutant) (11); □, TLPG01(pMRP9-1) (aer-2 mutant) (11); ⋄, PAO-CH1(pMRP9-1) (rpoS mutant); ▴, PAO-CH3(pMRP9-1) (aer-2 rpoS mutant); ▪, PAO-CH2(pMRP9-1) (aer rpoS mutant); ♦, PAO-CH1(pCSH9-11).