The Oxidative Stress Regulator RrpB Is Associated with a Genomic Hypervariable Region and Altered Oxidative Stress Resistance.

is the leading cause of bacterial foodborne diarrhoeal disease worldwide. Despite the microaerophilic nature of the bacterium, can survive the atmospheric oxygen conditions in the environment. Bacteria that can survive either within a host or in the environment like require variable responses to survive the stresses associated with exposure to different levels of reactive oxygen species. The MarR-type transcriptional regulators RrpA and RrpB have recently been shown to play a role in controlling both the oxidative and aerobic stress responses. Analysis of 3,746 and 486 genome sequences showed that whilst is present in over 99% of strains, the presence of is restricted and appears to correlate with specific MLST clonal complexes (predominantly ST-21 and ST-61). strains in contrast lack both and . In strains, the gene is located within a variable genomic region containing the IF subtype of the type I Restriction-Modification () system, whilst this variable genomic region in strains contains the IAB subtype system and not the gene. strains exhibit greater resistance to peroxide and aerobic stress than strains. Inactivation of resulted in increased sensitivity to peroxide stress in strains, but not in strains. Mutation of resulted in reduced killing of larvae and enhanced biofilm formation independent of status. The oxidative and aerobic stress responses of and strains suggest adaptation of within different hosts and niches that can be linked to specific MLST clonal complexes.