Figure 4.
Overexpression of the MexJK efflux system affects the expression levels of QS signaling genes. Total RNA was extracted for PAO1, ΔmexL, and ΔmexK at (A,B) early stationary (OD600 = 2.5) and (C,D) exponential phases of growth (OD600 = 0.6). The expression was determined by RT-qPCR for (A) genes regulated by QS, (B,C) genes responsible for QSSMs production, and (D) genes belonging to various RND pumping systems. The figure represents the fold change of the expression of these genes in the ΔmexL or ΔmexK strains, with respect to the one observed in PAO1. Values that are significantly different by an unpaired two-tail t-test are indicated by asterisks as follows: * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001.