Correlation Between Concentration of Hypothiocyanate and Antibacterial Effect of the Lactoperoxidase System Against Escherichia coli

Lactoperoxidase-catalyzed oxidation of thiocyanate ion results in a bactericidal effect against Escherichia coll. Ilypothiocyanate ion has been suggested to be the active agent formed during this reaction. Nonenzymatically prepared hypothiocyanate ion, however, only inhibited Eschericbia coli, and the bactericidal effect of the lactoperoxidase system was less stable than hypothiocyanate ion. These results suggest that hypothiocyanate ion is not the only antibacterial agent formed during the lactoperoxidase-catalyzed oxidation of thiocynate ion. The relationship between the loss of thiocyanate ion and formation of hypothiocyanate ion or bactericidal effect indicates that the higher oxyacids of thyocyanate ion, cyanosulfurous acid and cyanosulfuric acid also are formed at hydrogen peroxide concentrations giving a bactericidal effect and, thus, are involved in the effect of the lactoperoxidase system against Eschericbia coil