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Influence of the Pre-Harvest Environment on the Physiological State of Salmonella and Its Impact on Increased Survival Capability


Salmonella spp. has been implicated in numerous outbreaks of foodborne illness tied to the
consumption of fresh fruits, vegetables, and nuts, seeds and spices. Multistate outbreaks of
salmonellosis due to consumption of tomatoes, mangos, melons and raw almonds have
highlighted the ability of Salmonella to persist in a wide range of pre- and postharvest
environments. Exposure to large swings in moisture, temperature, and nutrient levels are
expected in these environments. The relative tolerance to these conditions is known differ
among strains of Salmonella. In addition, some of the environmental stressors may trigger a
variety of survival response mechanisms in some strains providing further competitive
advantage. While strain dependent survival phenomena have been documented, the mechanism
of these differences is not clear. <P>
The proposed research seeks to increase our understanding of
the environmental factors that trigger survival mechanisms in outbreak-related strains of
Salmonella and to better elucidate those mechanisms related to desiccation tolerance and
environmental persistence. <P>
The results will help the produce industry to better interpret
Salmonella-positive test results and should assist in making informed decisions related to preand
postharvest risks of contamination.

Harris, Linda
University of California - Davis
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