Location: Dairy and Functional Foods ResearchTitle: Pectic oligosaccharide structure-function relationships: prebiotics, inhibitors of Escherichia coli O157:H7 adhesion and reduction of Shiga toxin cytotoxicity in HT29 cells
|DI, RONG - Rutgers University|
|VAKKALANKA, MALATHI - Rutgers University|
|ONUMPAI, CHATCHAYA - University Of Reading|
|Chau, Hoa - Rose|
|RASTALL, ROBERT - University Of Reading|
|YAM, KIT - Rutgers University|
Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2017
Publication Date: 7/15/2017
Citation: Di, R., Vakkalanka, M.S., Onumpai, C., Chau, H.K., White, A.K., Rastall, R.A., Yam, K., Hotchkiss, A.T. 2017. Pectic oligosaccharide structure-function relationships: prebiotics, inhibitors of Escherichia coli O157:H7 adhesion and reduction of Shiga toxin cytotoxicity in HT29 cells. Food Chemistry. 227:245-254.
Interpretive Summary: Food-borne pathogens such as Escherichia coli are a major health concern. Biomass carbohydrates have the potential to prevent gut bacterial infections but more information is needed to determine which pectin structures are the most active. Five structurally different pectin fragment fractions were evaluated for fermentation by human fecal bacteria, promoting the growth of beneficial bacteria and inhibiting the adhesion of E. coli to human gut cells. Pectin structure-function relationships observed will be used to design appropriate animal and human feeding trials. These carbohydrates have the potential to join the arsenal of drugs for the therapy of bacterial diseases and health-promoting bioactive food ingredients.
Technical Abstract: Shiga toxin (Stx)-producing, food-contaminating Escherichia coli (STEC) is a major health concern. Plant-derived pectin and pectic-oligosaccharides (POS) that are abundant in biomass have been considered as prebiotics and for the protection of humans from Stx intoxication. Five structurally different POSs prepared from citrus peel were investigated in this study. Our results show that POS1, POS2 and MCP1 are bifidogenic with similar fermentability in human faecal samples with arabinose-rich POS2 having the greatest prebiotic potential for the modulation of human microbial populations. We demonstrate that all pectic substrates are anti-adhesive for E. coli O157:H7 to human HT29 cells but galacturonic acid-rich POS1 had the greatest anti-adhesive activity. Additionally, we show that all pectic substrates reduced the cytotoxicity of Stx2 holotoxin in HT29 cells as measured by the reduction of human rRNA depurination detected by our novel TaqMan-based RT-qPCR assay and POS1 performed best. Our competition ELISA results indicate that POS1 competes with Stx2 binding to the Gb3 receptor, underscoring the POS anti-STEC properties.