Rifampicin‐resistant RpoB S522L Vibrio vulnificus exhibits disturbed stress response and hypervirulence traits

Rifampicin resistance, which is genetically linked to mutations in the RNA polymerase β‐subunit gene rpoB, has a global impact on bacterial transcription and cell physiology. Previously, we identified a substitution of serine 522 in RpoB (i.e., RpoB(S522L)) conferring rifampicin resistance to Vibrio vulnificus, a human food‐borne and wound‐infecting pathogen associated with a high mortality rate. Transcriptional and physiological analysis of V. vulnificus expressing RpoB(S522L) showed increased basal transcription of stress‐related genes and global virulence regulators. Phenotypically these transcriptional changes manifest as disturbed osmo‐stress responses and toxin‐associated hypervirulence as shown by reduced hypoosmotic‐stress resistance and enhanced cytotoxicity of the RpoB(S522L) strain. These results suggest that RpoB‐linked rifampicin resistance has a significant impact on V. vulnificus survival in the environment and during infection.