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Title: Effect of fresh produce crop residue on the survival of Escherichia coli O157:H7 in soil

item Nou, Xiangwu
item Millner, Patricia
item Patel, Jitu
item Sharma, Manan
item Ingram, David

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2009
Publication Date: 7/13/2009
Citation: Nou, X., Millner, P.D., Patel, J.R., Sharma, M., Ingram, D.T. 2009. Effect of fresh produce crop residue on the survival of Escherichia coli O157:H7 in soil [abstract]. International Association for Food Protection 2009 Abstract Book. Paper No. T5-03. p. 41.

Interpretive Summary:

Technical Abstract: Introduction: Significant amounts of un-harvested crop residues are incorporated into the soil at the end of the growing seasons on leafy green produce fields. The extent to which these plant remnants contribute to persistence of soil and produce contamination by bacterial pathogens during the subsequent growing season is unclear. Purpose: The purpose was to evaluate the effects of decomposing plant residues on the survival and proliferation of E. coli O157:H7 in soil. Methods: Spinach leaves and soil were inoculated with several E. coli O157:H7 strains and buried in soil with leaves of cabbage, tubers of forage radish, or spinach. Survival and proliferation of inoculated pathogenic strains was measured for 35 days during biomass decomposition using MPN procedures. Results: No significant proliferation of E. coli O157:H7 strains occurred during the 5 wk biomass decomposition period. However, E. coli O157H7 survival was significantly affected by type of decaying biomass. When E. coli O157:H7-inoculated spinach leaves were exposed to cabbage biomass, the pathogen population declined by 5.0 log after 35 days of decomposition in soil, compared to 3.4, 3.0, and 3.3 log when exposed to biomasses of spinach, radish tubers, or soil without added biomass, respectively. Survival of E. coli O157:H7 inoculated from bovine fecal solids was not significantly affected when different types of crop biomass were tested. Significance: Cabbage and other brassicaceous plants have robust glucosinolate-myrosinase systems. Several glucosinalate hydrolysis products released during decomposition may reduce survival of bacterial pathogens under certain conditions (soil biofumigation). Data from this study suggests that biofumigation in conjunction with Brassica plant rotation could be an effective means in mitigating field contamination by bacterial pathogens in leafy green production systems.