Differential Effect of Paraquat and Hydrogen Peroxide on the Oxidative Stress Response in Vibrio Cholerae Non O1 26/06

ABSTRACT

Vibrio cholerae non O1 26/06, a non-pathogenic strain, was subjected to treatment by different concentration of paraquat (PQ) and H₂O₂. Exposure to PQ for 1 h caused induction of reactive oxygen species (ROS) such as superoxide anion radical (^•O₂⁻) and H₂O₂. At the same time, second stress factor significantly inhibited ^•O₂⁻ production and enhanced the intracellular H₂O₂ content. The enhanced ROS generation resulted in a significant increase in the levels of oxidatively damaged proteins in comparison to the control variant. Thus, the exposure of V. cholerae cells to PQ and H₂O₂ promoted oxidative stress. Cell response against this stress includes activation of antioxidant enzyme defence. The treatment with PQ concentrations in the range of 0 - 5 mM resulted mainly in activation of SOD, but not noticeably changed CAT activity in V. cholerae non-O1 26/06. In contrast, effect of H₂O₂treatment on antioxidant enzyme synthesis in our Vibrio strain was still much more pronounced for CAT than for SOD. Therefore, oxidative stress responses induced by ^•O₂⁻ (generated intracellularly by PQ) and H₂O₂ demonstrated differential adaptation of Vibrio cells to different toxic agents.

Keywords:

• Vibrio cholerae
• superoxide dismutase
• oxidative stress
• paraquat