Pectic oligosaccharide structure-function relationships: Prebiotics, inhibitors of Escherichia coli O157:H7 adhesion and reduction of Shiga toxin cytotoxicity in HT29 cells

Food Chem. 2017 Jul 15;227:245-254. doi: 10.1016/j.foodchem.2017.01.100. Epub 2017 Jan 21.


Shiga toxin (Stx)-producing, food-contaminating Escherichia coli (STEC) is a major health concern. Plant-derived pectin and pectic-oligosaccharides (POS) have been considered as prebiotics and for the protection of humans from Stx. Of five structurally different citrus pectic samples, POS1, POS2 and modified citrus pectin 1 (MCP1) were bifidogenic with similar fermentabilities in human faecal cultures and arabinose-rich POS2 had the greatest prebiotic potential. Pectic oligosaccharides also enhanced lactobacilli growth during mixed batch faecal fermentation. We demonstrated that all pectic substrates were anti-adhesive for E. coli O157:H7 binding to human HT29 cells. Lower molecular weight and deesterification enhanced the anti-adhesive activity. We showed that all pectic samples reduced Stx2 cytotoxicity in HT29 cells, as measured by the reduction of human rRNA depurination detected by our novel TaqMan-based RT-qPCR assay, with POS1 performing the best. POS1 competes with Stx2 binding to the Gb3 receptor based on ELISA results, underlining the POS anti-STEC properties.

Keywords: Anti-adhesion; HT29 cells; Orange pectic oligosaccharides; STEC; Shiga toxin 2; TaqMan RT-qPCR; rRNA depurination.

MeSH terms

  • Bacterial Adhesion*
  • Escherichia coli Infections / microbiology*
  • Escherichia coli O157 / genetics
  • Escherichia coli O157 / physiology*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Feces / microbiology
  • HT29 Cells
  • Humans
  • Oligosaccharides / chemistry*
  • Oligosaccharides / metabolism
  • Pectins / chemistry
  • Pectins / metabolism*
  • Prebiotics / analysis*
  • Shiga Toxin / metabolism
  • Shiga Toxin / toxicity*


  • Escherichia coli Proteins
  • Oligosaccharides
  • Prebiotics
  • Shiga Toxin
  • Pectins