Summary of Awards to Date

Impacts of irrigation water quality on the persistence and transmission of E.Coli O157:H7 from soil to plants.

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Dec. 1, 2007 - Nov. 30, 2010

Award Number


Funding Agency

Center for Produce Safety

Amount Awarded



Abasiofiok Mark Ibekwe, Ph.D.
US Salinity Laboratory, ARS-USDA


Organic amendments and waste water frequently contain high levels of salinity, and can be a major factor in altering the root systems of plants to facilitate the entry and transport of bacteria into plant tissues. There has been no research to date that has revealed a "kill" step that both reliably destroys pathogenic contamination and retains a level of quality acceptable to consumers. Consequently, contamination by the pathogen must be prevented at all steps of the supply chain, and the first step to accomplish this begins in the field. The most likely sources of E. coli O157:H7 in the production (growing) environment include some of the following: irrigation water quality and manure (feces) associated with cattle and to some extend workers and wildlife. A major objective of this study will be the acquisition of knowledge on risk factors that affect the growth and spread of E. coli O157:H7 on field crops and that can be used to model the likelihood for spread of the pathogen on crop plants. Our studies will focus in particular on identification of genes that are used by E. coli O157:H7 during colonization and growth on plants, and which therefore may influence survival and spread of the pathogen within the field. The data that we will obtain from these studies will then be used to develop models for prediction of how E. coli O157:H7 is influenced by different environmental factors, agricultural practices, and interactions with the indigenous microflora.