title: Role of reactive oxygen species in Escherichia coli inactivation by cupric ion.
abstract: This study demonstrated Escherichia coli inactivation by cupric ion (Cu[II]), focusing on intracellular generation and consumption of reactive oxygen species (ROS) including superoxide and hydroxyl radials. In the presence of Cu(II), intracellular superoxide levels of E. coli decreased in a concentration-dependent manner, indicating that superoxide radical was used to reduce Cu(II) to Cu(I) in cells. The variation in the hydroxyl radical level by adding Cu(II) was negligible. Molecular oxygen and hydroxyl radical scavengers did not affect the inactivation efficacy of E. coli by Cu(II), excluding the possibility that hydroxyl radicals induced by the copper-mediated reduction of oxygen contributed to the microbiocidal action of Cu(II). However, the inactivation of E. coli by Cu(II) was considerably inhibited and accelerated by a Cu(I)-chelating agent and a Cu(II)-reducing agent, respectively. Our results suggest that the microbiocidal action of Cu(II) is attributable to the cytotoxicity of cellularly generated Cu(I), which does not appear to be associated with oxidative damage by Cu(I)-driven ROS.
authors.affiliation: World Class University (WCU) program of Chemical Convergence for Energy & Environment (C2E2), School of Chemical and Biological Engineering, College of Engineering, Institute of Chemical Process, Seoul National University (SNU), Seoul 151-744, Republic of Korea.
authors.forename: Hee-Jin
authors.initials: HJ
authors.lastname: Park
authors.forename: Thuy T M
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Jeyong
authors.initials: J
authors.lastname: Yoon
authors.forename: Changha
authors.initials: C
authors.lastname: Lee
mesh_terms: D003300:Copper / Q000737:chemistry / Q000633:toxicity*; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D015386:Hazardous Substances / Q000633:toxicity*; D007477:Ions / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism*
chemical_list: D015386:Hazardous Substances; D007477:Ions; D017382:Reactive Oxygen Species; D003300:Copper