VIEW ARTICLE

Enhancement of the Bactericidal Activity of a Peroxidase System by Phenolic Compounds. N. V. Rama Raje Urs, Post-doctoral Research Associate, Department of Botany and Plant Pathology, Iowa State University, Ames 50010; J. M. Dunleavy, Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, and Professor, Department of Botany and Plant Pathology, Iowa State University. Phytopathology 65:686-690. Accepted for publication 25 January 1975. DOI: 10.1094/Phyto-65-686.

A reaction mixture bactericidal to Xanthomonas phaseoli var. sojensis, a pathogen of soybeans, consisted of horseradish peroxidase, potassium iodide, and hydrogen peroxide. Incubating the bacteria (10⁶/ml) with the reaction mixture for 30 minutes at 37 C decreased the viable cell count from 10⁶ to 10⁴ cells/ml. Catechol, scopoletin, guaiacol, hydroquinone, 8 - hydroxyquinoline, and ferulic, caffeic, cinnamic, and protocatechuic acids enhanced the bactericidal activity, but coumarin, resorcinol, and gallic acid had no effect at concentrations tested. Preincubation of the reaction mixture for 30 minutes and incubation with the bacterial cells for 30 minutes revealed that the oxidative products of 8 - hydroxyquinoline, hydroquinone, catechol, and guaiacol reduced the viable cell number to fewer than 30 cells/ml.