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D. J. O'SULLIVAN, Dept. of Food Science & Nutrition, Univ. of Minnesota, 1334 Eckles Ave., 225 Food Science & Nutrition Bldg., Saint Paul, MN 55108-6099 The lactic acid bacteria (LAB), and other bacteria used in food fermentations, are the primary microorganisms used in foods to protect against spoilage and pathogenic bacteria. As they are fermentative bacteria, they can produce a variety of metabolites, such as lactic acid, acetic acid, diacetyl and many other byproducts of metabolism with antimicrobial capabilities. Many also produce hydrogen peroxide and other radicals that originate from oxygen metabolism. Besides these byproducts of metabolism, some cultures can produce bacteriocins, which are secreted proteinaceous compounds whose purpose is to inhibit the growth of closely related bacteria. Numerous bacteriocins from the LAB have been characterized and it is noteworthy that while most only inhibit closely related bacteria, in some cases only strains within the species, some have a much wider spectrum of activity. Nisin is an example of a bacteriocin with a wide spectrum of activity, inhibiting almost all gram positive bacteria, and is the most thoroughly studied bacteriocin. From a food safety perspective, it is much more desirable to use a culture producing a broad spectrum bacteriocin in particular food processes. Techniques are currently available to engineer fermentation cultures to produce different bacteriocins or other antimicrobial metabolites. This presentation will cover some of the important techniques that are available for this purpose and will look at examples. It will also introduce the area of culture genomics and discuss how this can open the door for engineering ‘designer’ cultures that can be optimized for the production of any particular metabolite.
Session 20, Application and use of genomics in food microbiology
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