ARS | Publication request: ORANGE PULP REDUCES GROWTH OF E. COLI O157:H7 AND SALMONELLA TYPHIMURIUM IN PURE CULTURE AND IN VITRO MIXED RUMINAL MICROORGANISM FERMENTATION

Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2005
Publication Date: July 24, 2005
Citation: Callaway, T.R., Carroll, J.A., Arthington, J.D., Anderson, R.C., Edrington, T.S., Genovese, K.J., Nisbet, D.J. 2005. Orange pulp reduces growth of Escherichia coli O157:H7 and Salmonella typhimurium in pure culture and in vitro mixed ruminal microorganism fermentation [abstract]. Journal of Animal Science. 83(Suppl. 1):236.

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.