Relative quantitation of genes by real-time quantitative polymerase chain reaction. The samples were used for quantitation in the ABI 7500 Sequence Detector System (Applied Biosystems). The measures were normalized using threshold cycles (Ct) obtained for the amplifications of the endogenous control run in the same plate. The values represent the fold increase in gene expression compared with the values obtained for cDNA from planktonic cells (calibrator). The results are averages of three biological repetitions. Asterisk indicates significant difference (P ≤ 0.05) between the mean values compared to the control.