Dose-response relationships. A model for describing interactions, and its application to the combined effect of nisin and lactic acid on Leuconostoc mesenteroides

As well as producing bacteriocins, many lactic bacteria produce other poten tially toxic compounds or growth inhibitors, especially lactic acid, which may interfere in the assays commonly used to quantify these peptides. A sys tematic set of modifications is proposed which, when applied to the logisti cal equation, enable it to describe the combined (but not additive) effects of two or more active principles. The general model thus derived is applie d to the interaction of nisin and lactic acid on Leuconostoc mesenteroides.