Evaluation of the role hydroxyl radicals and iron play in hydrogen peroxide killing of Xanthomonas campestris pv. phaseoli

Abstract

Hydroxyl radical, a product of H2O2metabolism in the Fenton reaction, is a major reactive oxygen species involved in H2O2killing of Xanthomonas campestris pv. phaseoli (Xp). Compounds which absorbed hydroxyl radicals protected Xanthomonas from H2O2killing, but not from killing by a superoxide generator or an organic peroxide. Addition of iron potentiated H2O2killing. On the other hand, pre-treatment of Xp with an iron chelator showed no protective effects and H2O2killing was actually enhanced. Unexpectedly, resuspension of Xp in either water or phosphate buffer induced high-level resistance to H2O2killing. The unknown protection mechanism was independent of new protein synthesis. Copyright (C) 1998 Federation of European Microbiological Societies.