Relative change in transcription level during acid stress of selected genes: dps , cj0706 , sodB , trxB , ahpC , mogA , p19 and fur analyzed by qRT-PCR. C. jejuni strain NCTC 11168 was grown to 1 × 108CFU/ml and exposed to HCl (pH 5.2) and acetic acid (pH 5.7). The expression level of acid stressed for a specific gene was compared with unstressed cells and the horizontal line illustrates the fold change at 1.0 for the reference genes (rpoA and lpxC). Fold changes and standard deviations were calculated from the outcome of qRT-PCR runs from three microbiological independent experiments. Genes marked with an asterisk are significantly over-expressed compared with genes from non-stressed cells.