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J. FRANK, Dept. of Food Science & Technology, Univ. of Georgia, Athens, GA 30605 Specific genotypes of Listeria monocytogenes have been repeatedly isolated from food processing environments, sometimes over periods of years. The presence of these persistent strains presents a risk of product contamination, so efforts must be made to eliminate them from the plant environment. Some studies have shown that persistent strains have enhanced attachment capabilities or sanitizer resistance, whereas other studies show no such relationships. The inability to identify a consistent phenotype associated with persistence may be because repeated isolation of specific genotypes over time can have multiple causes. These include growth of the strain at a specific growth niche not targeted by plant sanitation, adaptation of the strain to stress allowing it to survive ineffective cleaning and sanitation, and repeated introduction of the genotype from another source. Phenotypic characteristics that could enhance strain persistence include attachment ability, biofilm formation, ability to grow in mixed culture biofilms, and adaptation to stresses associated with sanitizers, heat, dehydration, and starvation. The relative contribution of these characteristics to strain persistence is unknown.
Session 6, Foodborne pathogens in the food processing environment and their control
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |