Fig. 4.

Environment-specific QS gene response. Cluster analysis (14) of genes that show CF respiratory liquid-specific patterns of QS-dependent expression not previously identified under laboratory growth conditions. Indicated in the first column are genes showing a >5-fold change in expression in wild-type P. aeruginosa relative to a rhlR, lasR double mutant, both grown in M63 medium containing 10% MPM. Green and red depict QS-dependent genes that are repressed or activated, respectively, in 10% MPM. The second through fifth columns represent the expression pattern of these genes at the indicated culture densities (OD₆₀₀) in laboratory medium supplemented with synthetic autoinducers (rhlI, lasI mutant with added autoinducers versus no autoinducer). Genes in green and red are repressed and activated, respectively, by the addition of exogenous autoinducers. Genes in black are QS-independent (<2-fold change). Data for growth phase-dependent gene expression in the presence of P. aeruginosa QS autoinducers has been published (15).