Fuente: WIPO "dairy products" Peroxidase systems such as the Lactoperoxidase system (LPS) are combined with antimicrobial fatty acids or fatty acid derivatives to produce a synergistic antimicrobial composition. These compositions are disclosed as being useful for rendering surfaces, and also products such as food or cosmetics, resistant to microbes. A preferred form of the composition contains lactoperoxidase, monolaurin or sodium dodecyl sulphate, a source of peroxide, and thiocyanate ions.