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Comparison of Surrogate E. Coli Survival and Epidemiology in the Phyllosphere of Diverse Leafy Green Crops


The validation and application of surrogates, safe substitutes for pathogens, to study critical aspects of contamination, spread of contaminants during handling, open-environment ecological studies of survival during production, and controls and interventions during processing has had immeasurable value with many food borne pathogens. <P>
Specific isolates of nonpathogenic E. coli that have been selected for environmental, soil, and leaf surface fitness on lettuce and spinach will be further qualified as surrogates for E. coli O157:H7. These will be made available to the research community to facilitate broad controlled environment and field-based experiments simulating pathogen dispersal, survival, and growth potential on lettuce and leafy greens. <P>
Up to fourteen different types and varieties of leafy greens including leaf lettuce, spinach, endive, and mini-greens used in Spring Mix salads will be tested in two seasonal plantings for their comparative capacity to support growth of surrogate E. coli. A separate field trial will investigate the affect of nitrogen application levels on surrogate E. coli survival and growth. <P>
By conducting these tests, the database that supports the establishment of industry standards for microbiological quality will be significantly expanded. In separate but related efforts, a regional team of Cooperative Extension Advisors and a campus-based Extension Specialist will conduct detailed microbiological grid-analysis of grower/handler fields, identified as positive for foodborne pathogens, to help identify risk factors and localize natural contamination events. <P>
These findings will be widely shared to improve collective food safety management and the best use of rapid pathogen detection screening by the leafy greens industry.

More information

<P>View the <a href="; target="_blank">Final Project Report </a> at the <a href="; target="_blank">Center for Produce Safety website</a>.

Suslow, Trevor
University of California - Davis
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