qRT-PCR monitoring the expression of selected genes from PA adapted and unadapted cultures. The level of expression of each target gene in the PA adapted culture was compared to the level of gene expression of the identical target in the unadapted culture. The expression of each gene in unadapted cultures was taken to be the basal level of expression for that particular gene to which the expression in PA adapted cultures was compared, therefore allowing quantification of the relative changes in gene expression of selected targets. The relative quantification (RQ) of each target gene was subsequently calculated from the qRT-PCR data using the comparative CT (ΔΔCT) method. All data obtained from qRT-PCR experiments were normalized using 16 s rRNA. Presented data is the average of five independent trials. Standard error is represented by error bars. Genes with expression that is significantly different from the unadapted condition are indicated with an asterisk.