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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #337551

Research Project: Characterization and Mitigation of Bacterial Pathogens in the Fresh Produce Production and Processing Continuum

Location: Environmental Microbial & Food Safety Laboratory

Title: The effect of soil management on the persistence of E. coli and Listeria spp. in manure- amended soils in the Northeast United States

item LEKKAS, PANGIOTIS - University Of Vermont
item Sharma, Manan
item NEHER, DEBORAH - University Of Vermont
item WEICHT, THOMAS - University Of Vermont
item Millner, Patricia
item DONNELLY, CATHERINE - University Of Vermont

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Introduction: Enterohemorrhagic Escherichia coli and Listeria monocytogenes can contaminate leafy greens through inappropriately managed raw manure applied to soils. Current FDA guidance includes calling for additional scientific data to determine the appropriate interval between application of manure and harvest of crops grown in manure-amended soils to minimize risk of human illness. Purpose: To determine persistence of E. coli and Listeria spp. populations in sandy and loamy soils amended with dairy-manure solids (DS) in Vermont. Methods: One liter of a three-strain inoculum (TVS353,TVS354, and TVS355) of rifampicin-resistant E. coli (rEc) (6 log CFU/ml)was sprayed onto field plots (2m2) of either loamy sand (L) or sandy (S) soils amended with DS or no manure (NM). DS was either tilled into soil or spread on the surface. Survival of inoculated rEc, naturally present E. coli (nEC) and Listeria spp. in DS in untilled and tilled plots were quantified over 56 days-post-inoculation (dpi) by direct plating or MPN. Results: By 56 dpi, in surface plots, rEc populations declined by 3.65 – 3.69 log CFU/g and 3.05-3.11 log CFU/g in L and S soils, respectively. In tilled plots, rEc populations declined by 2.27- 2.33 and 2.08 – 2.14 log CFU/g in L and S soils, respectively. In L and S soils, rEc populations in surface NM declined to undetectable levels by 14 and 28 dpi, respectively. Overall, Listeria spp. populations increased by 0.05-0.96 log MPN/g by day 56, and Listeria spp. were present in both NM and DM-amended soils. Populations of nEc declined by 1.15-1.60log CFU/g by 56 dpi. Significance: In comparison to studies conducted in the two previous years at the same sites, rEc populations declined more rapidly by 7 dpi in this iteration. Results presented from this year’s study indicates that soil tillage influences survival of E. coli as much as dairy manure amendment.