Microbial Inactivation by Cupric Ion in Combination with H2O2: Role of Reactive Oxidants
2013
Nguyen, Thuy T. M. | Park, Hee-Jin | Kim, Jee Yeon | Kim, Hyung-Eun | Lee, Hongshin | Yoon, Jeyong | Lee, Changha
The cupric ion mediated inactivation of Escherichia coli was enhanced by the presence of hydrogen peroxide (H₂O₂), with increasing inactivation efficacy observed in response to increasing concentrations of H₂O₂. The biocidal activity of the Cu(II)/H₂O₂ system is believed to result from the oxidative stress caused by reactive oxidants such as the hydroxyl radical (•OH), cupryl species (Cu(III)), and the superoxide radical (O₂•–), which are produced via the catalytic decomposition of H₂O₂. In E. coli cells treated with Cu(II) and H₂O₂, the intracellular level of •OH and Cu(III) increased significantly, leading to complete disruption of cell membranes. On the basis of experimental observations made using an •OH scavenger, copper-chelating agents, and superoxide dismutase, it is concluded that Cu(III) is the predominant species responsible for the death of E. coli cells. It was also found that the production of Cu(III) was promoted by the reactions of copper with intracellular O₂•–. MS2 coliphage was found to be even more susceptible than E. coli to the oxidative stress induced by the Cu(II)/H₂O₂ system.
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