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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 #321070
Title: Brassica vegetables as a green manure to control Escherichia coli O157:H12 in soil

Author
item Patel, Jitu

Submitted to: UJNR Food & Agricultural Panel Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/17/2015
Publication Date: 11/15/2015
Citation: Patel, J.R. 2015. Brassica vegetables as a green manure to control Escherichia coli O157:H12 in soil. UJNR Food & Agricultural Panel Abstracts. p.4.

Interpretive Summary:

Technical Abstract: Plant remnants tilled over in soil after harvest of Brassica crops may possess antimicrobial from exudates secreted in soil following residual incorporation (till over). We investigated the role of broccoli remnants tilled over after harvest for reducing enteric pathogens in soil. The glucosinolate-hydrolyzed compounds (GHC) obtained commercially were evaluated for their antibacterial activity using a disc diffusion assay on tryptic soy agar (TSA). Salmonella were more sensitive to these compounds than E. coli O157:H7 or non-pathogenic E. coli. Benzyl isothiocyanate (BIT) exhibited a significantly higher zone of inhibition than other antimicrobials or Gentamicin (positive control) against Salmonella strains. Three broccoli cultivars: Arcadia, Belstar, and Diplomat were grown in a greenhouse to determine their glucosinolate (GSL) content by high performance liquid chromatography - mass spectrometry (HPLC- MS). The GSL of broccoli varied with cultivar and its fraction; glucotrapaeolin content was up to 10x higher in roots of the Diplomat cultivar than in roots of Arcadia or Belstar. Broccoli (Pacman cultivar) grown at Beltsville farm was tilled over after harvest and soil was spray-inoculated with E. coli O157:H12 strain (7 log CFU/ml) followed by additional treatment of glucosinolate or plant antimicrobials. E. coli O157:H12 populations in BIT-treated soil were not detected by direct plating after 7 days, whereas populations ranged from 0.9 to 2.0 Log CFU/g of soil treated with other antimicrobials. The field study repeated with five broccoli cultivars (Arcadia, Diplomat, Green Magic, Belstar, and Imperial) revealed differences in the E. coli O157:H12 persistence with type of broccoli cultivars tilled over in soil. E. coli O157:H12 were undetectable after 12 weeks in soil tilled over with Green magic and Imperial broccoli cultivars. The results shows that the tilling over of the broccoli remnants as a green manure after harvest as well as GDC has the potential in reducing E. coli O157:H12 populations in soil.