Role of the Alkyl Hydroperoxide Reductase Subunit C1 Gene in Vibrio parahaemolyticus Against Hydrogen Peroxide.

Vibrio parahaemolyticus is a major marine foodborne pathogen and has been a global public health concern since the emergence of pandemic strains in 1996. The catalase KatE1 and alkyl hydroperoxide reductase subunit C1 (AhpC1) are important components of the oxidative stress defense system in this bacterium. In this study, we investigated the role of AhpC1 in protection against H₂O₂-induced oxidative stress using the ΔkatE1, ΔahpC1, ΔkatE1ΔkatE2, and ΔkatE1ΔahpC1 mutant strains of V. parahaemolyticus. Under H2O2 exposure, the ΔkatE1ΔkatE2 mutant showed the highest sensitivity, whereas the ΔkatE1ΔahpC1 mutant exhibited intermediate sensitivity relative to the wild-type strain. Similarly, intracellular reactive oxygen species accumulation was highest in the ΔkatE1ΔkatE2 mutant and moderately increased in the ΔkatE1ΔahpC1 mutant. The ΔkatE1ΔahpC1 mutant also retained a higher level of residual extracellular H₂O₂, which was significantly reduced by complementation with the ahpC1. In addition, ahpC1 expression was detected under normal conditions and appeared to increase following H2O2 treatment. In summary, these findings suggest that AhpC1 functions alongside catalase systems in the oxidative stress defense network of V. parahaemolyticus.