POTENTIAL FOR BIOLOGICAL-CONTROL OF AGENTS OF FOODBORNE DISEASE

The competitive interaction of bacteria is well recognized. Natural an d controlled food fermentations serve as typical examples of competiti ve inhibition. Some bacteria produce antagonistic substances (bacterio cins) that are active against other closely related bacteria, in addit ion to the inhibitory action of pH, organic acids or hydrogen peroxide . Nisin, produced by strains of Lactococcus lactis subsp. lactis, is a n excellent example of a relatively broad spectrum bacteriocin that is active against several Gram-positive bacteria, including spore-formin g bacteria. Nisin is used as a preservative agent in foods in many cou ntries, and its production by L. lactis in foods is being studied as a n approach to safety assurance. Unfortunately nisin is not suitable fo r use in all food systems because of its limited solubility above pH 5 and its instability in some foods. Production of bacteriocins by lact ic acid bacteria from dairy, meat and vegetable foods is the focus of many current research studies. The biological effect, genetic control and chemical structure is being studied to determine the potential for other bacteriocins or bacteriocinogenic strains of lactic acid bacter ia as agents for control of foodborne pathogens and spoilage bacteria.