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United States Department of Agriculture

Agricultural Research Service

Research Project: MICROBIAL ECOLOGY AND SAFETY OF FRESH PRODUCE

Location: Environmental Microbial and Food Safety Laboratory

Title: The Antimicrobial effects of Glucosinolates Hydrolysis compounds on E. Coli O157:H12 into field soil

Authors
item PATEL, JITU
item Macarisin, Dumitru
item Yossa, Nadine -
item Chauhan, Paroo

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 18, 2013
Publication Date: N/A

Technical Abstract: Introduction: Soil can be a source of pre-harvest contamination of produce by pathogens. Natural antimicrobials such as glucosinolate-hydrolyzed products (GHP) found in Brassicaceae family crops can be used as a green manure to control enteric pathogens in soil. Purpose: The antimicrobial activity of GHP against Salmonella and E. coli O157:H7 was evaluated. A field study was conducted to evaluate the ability of GHP and broccoli residues to control E. coli O157:H12 in organic soil. Methods: Isothiocyantes (benzyl-, butyl-, ethyl-, isopropyl-, methyl-, phenethyl-, allyl-), Indole methyl oxazolidinone, and methyl propyl pyrazole carboxylic acid were evaluated for antibacterial activity using a disc diffusion assay on Tryptic soy agar (TSA). Five strains of Salmonella or E. coli O157:H7 were individually spread-plated on TSA (50 µL, 6 log CFU/ml) and 6-mm sterile filter disk impregnated with 15 µL GHP was overlaid. Following 24 h incubation at 37°C, zone of inhibition was measured. Broccoli florets and Benzyl isothiocynate (BIT, 0.013%) was incorporated in soil inoculated with E. coli O157:H12 (5.5 log CFU/g) and raked for uniform dispersion. Surviving E. coli O157:H12 populations in treated soil (n=90) were determined for 98 days by spiral plating on CT-SMAC NA and by 3-tube MPN procedure. Results: BIT (10 mg/ml) exhibited significantly higher zone of inhibition than other GHPs or gentamicin (positive control) against Salmonella strains. Salmonella Negev was the most sensitive serovar to BIT. The antibacterial effects of BIT and other GHPs against E. coli O157:H7 were comparable to gentamicin. BIT treatment reduced E. coli O157:H12 by 3 log CFU (P < 0.05) in 14 days. The E. coli O157:H12 were undetectable (< 0.4 Log CFU/g) after 56 days in BIT- and broccoli-treated soil. Significance: Current study demonstrates Brassicaceae family crops can be used as a green manure to control enteric pathogens in soil contaminated with compost or irrigation water

Last Modified: 7/28/2014
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