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United States Department of Agriculture

Agricultural Research Service

Research Project: INTERVENTIONS TO REDUCE EPIZOOTIC PATHOGENIC BACTERIA IN SWINE AND CATTLE Title: Citrus products decrease growth of E. coli O157:H7 and Salmonella Typhimurium in pure culture and in fermentation with mixed ruminal microorganism in vitro

item Callaway, Todd
item Carroll, Jeffery
item Arthington, J - UNIVERSITY OF FLORIDA
item Pratt, Chelsea
item Edrington, Thomas
item Anderson, Robin
item Nisbet, David

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 18, 2008
Publication Date: October 14, 2008
Repository URL:
Citation: Callaway, T.R., Carroll, J.A., Arthington, J.J., Pratt, C.B., Edrington, T.S., Anderson, R.C., Ricke, S.E., Crandall, P., Nisbet, D.J. 2008. Citrus products decrease growth of E. coli O157:H7 and Salmonella Typhimurium in pure culture and in fermentation with mixed ruminal microorganism in vitro. Foodborne Pathogens and Disease. 5:621-627.

Interpretive Summary: Foodborne pathogens can live within the gut of food animals and non-antibiotic methods to reduce pathogens in the live animal are critical to improving food safety. Citrus by-products (orange peel and pulp) often are fed to animals because of their high nutritive value and low cost and these contain essential oils (e.g., limonene) that are natural antimicrobials. Our results indicate that citrus products included in ruminant rations decreased ruminal populations of E. coli O157:H7 and Salmonella Typhimurium without causing a significant change in fermentation endproducts. Based on our data, it appears that orange pulp provides an antipathogenic activity in a vehicle that is amenable to current production practices, is palatable to the consumer as a “green” solution, is economically feasible, and is available to the producer currently.

Technical Abstract: Orange peel and orange pulp are by-product feeds that are included in cattle rations in regions of the U.S. where citrus fruits are grown and processed. They are included in feedlot and dairy cattle rations due to their low cost, nutritional qualities, and palatability. The antimicrobial activity of citrus oil and other citrus-derived products have been previously reported. Escherichia coli O157:H7 and Salmonella spp. are human food borne pathogenic bacteria that can be carried in the gastrointestinal tract of cattle. Therefore, the present study was carried out to determine if citrus products in a cattle ration exert antimicrobial effects on E. coli O157:H7 and Salmonella typhimurium populations. The specific growth rate of pure cultures (n = 3) of E. coli O157:H7 and Salmonella typhimurium were significantly (P < 0.05) reduced by addition of 2% (w/v) orange pulp and orange peel. Ruminal fluid was collected from cattle (n = 2), diluted with growth medium containing 1 g/l soluble starch, and E. coli O157:H7 or Salmonella typhimurium were added to the ruminal fluid. The addition of orange pulp and peel to in vitro mixed ruminal microorganism fermentations (n = 2) demonstrated that both orange pulp and peel reduced E. coli O157:H7 and Salmonella typhimurium populations at least 2 log10 in mixed ruminal fluid fermentations. Other in vitro ruminal fermentations (n = 3) contained E. coli O157:H7 or Salmonella typhimurium and contained additions of: 0, 0.05, 0.1, 0.25, 0.5, 1.0, 2.0 % (w/v) of feed-grade orange pulp. Addition of orange pulp reduced (P < 0.05) E. coli O157:H7 populations from 10**5 to 10**2 CFU/ml and Salmonella typhimurium populations (P < 0.05) from 10**4 to 10**2 CFU/ml. These results indicate that orange pulp and/or peel included in ruminant rations could decrease ruminal populations of food-borne pathogenic bacteria. Further research is needed to determine if the antimicrobial activity of orange products against E. coli O157:H7 or Salmonella Typhimurium continues in the lower gastrointestinal tract.

Last Modified: 8/27/2015
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