FIG. 4.

Effects of perR and fur mutations on oxidative-stress resistance of C. jejuni wild type and mutants to CHP (A) and hydrogen peroxide (B). Resistance is expressed as the zone of growth inhibition after overnight growth on agar plates. Resistance was measured against 3% (open bars) and 10% (closed bars) CHP and H₂O₂. The error bars represent data from three separate plates. The perR mutation derepresses expression of AhpC and KatA and results in the perR mutants showing hyperresistance to CHP and H₂O₂. The fur mutation on its own slightly decreases resistance to both CHP and H₂O₂, whereas the fur perR double mutant is more resistant to CHP and H₂O₂. The perR mutants did not show an inhibition zone with 3% H₂O₂ (asterisk).