Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2008
Publication Date: 6/14/2008
Citation: Rhoads, J., Manderson, K., Hotchkiss, A.T., Gibson, G.R., Formentin, K., Beer, M., Rastall, R.A. 2008. Pectic oligosaccharide mediated inhibition of the adhesion of pathogenic escherichia coli strains to human gut culture cells. Journal of Food Protection 71:2272-2277. Interpretive Summary: The enormous volume of fruit and vegetable processing residues, such as orange peels and sugar beet pulp, represents an underutilized domestic resource of valuable health-promoting compounds. These residues have been used as cattle feed ingredients, but as such their value is low (< 5 cents/pound) and there is more supply than demand for cattle feed. However, these residues are rich in valuable carbohydrates. Escherichia coli (E. coli) is a serious bacterial pathogen of our food supply. These bacteria produce toxins that bind to carbohydrate receptors on the intestinal surface. Carbohydrates that mimic the structure of these receptors can competitively inhibit the binding of food pathogen toxins. We demonstrated, for the first time, that carbohydrates derived from pectin found in orange peel can competitively inhibit the binding of E. coli and its toxins to colon tissue culture cells and receptors, respectively. Orange peel is an inexpensive source of health-promoting carbohydrates that can be used as functional food and animal feed ingredients. Development of these carbohydrates into commercial products will add value to citrus processing residues and will benefit citrus growers and processors.
Technical Abstract: Pectic oligosaccharides (POS) were investigated for their ability to inhibit the adhesion of three strains of verotoxigenic Escherichia coli (VTEC), three strains of enteropathogenic E. coli (EPEC), Lactobacillus acidophilus, L. gasseri and Desulfovibrio desulfuricans to human HT29 tissue cell cultures. POS exerted effective antiadhesive properties at a dose of 2.5 mg/ml, reducing adhesion of EPEC and VTEC strains to less than 30% of their control values. IC50 values for EPEC and VTEC ranged from 0.15 to 0.46 mg/ml. The probiotic organism L. acidophilus was unaffected by POS, but adhesion of L. gasseri was reduced to 29% of the control. POS very strongly reduced the adhesion of Dsv desulfuricans to 0.33% of the control value. POS also had a protective effect against E. coli verocytotoxins VTI and VTII with protection seen at POS concentrations of 0.01 and 1 microgram/ml respectively. The POS may therefore be applicable as anti-adhesive agents against certain Gram negative pathogens.