(P20-004-23) Effect of Carbohydrate Structure on Biological Function: Mannan-oligosaccharides and Control of Pathogens

Objectives: Pathogens residing within the gastrointestinal (GI) tract compromise human health, and the rising incidence of antibiotic-resistant bacterial strains has resulted in initiatives seeking alternative treatments. Prebiotic oligosaccharides may be one such alternative, due to their ability to modulate the composition of the gut microbiome. In addition to stimulating the growth of commensal bacteria and “crowding out” pathogens, some prebiotics such as mannan-oligosaccharides (MOS) can act as molecular decoys, directly binding to the surface of some pathogenic bacteria and preventing their adhesion to intestinal epithelial cells.

While structural characteristics such as monomer composition and degree of polymerization are known to influence the biological function of carbohydrates, little is known about structure-function relationships for MOS. Therefore, the focus of this work is to (1) explore the impact of structural characteristics of MOS on pathogen and commensal bacterial growth, and (2) compare the effectiveness of MOS in controlling pathogens to other, well-characterized prebiotics.

Methods: Structural characterization of MOS was performed using high performance liquid chromatography and liquid chromatography mass spectrometry. The minimum inhibitory concentration (MIC) was assessed for MOS and other commercial prebiotics FOS and inulin against pathogens E. coli, L. monocytogenes, and ESKAPE pathogen K. pneumoniae. Growth studies using MOS, FOS, and inulin were performed for commensal bacterial strains L. reuteri, L. rhamnosus, and L. plantarum.

Results: Growth of E. coli, L. monocytogenes, and K. pneumoniae was effectively inhibited by MOS in a dose-response manner, and superior inhibition was observed for MOS compared to FOS and inulin. Cultures of L. reuteri, L. rhamnosus, and L. plantarum showed better growth when growing in media supplemented with MOS than with inulin, and comparable growth to that with FOS.

Conclusions: This research will inform further investigations of the ability of prebiotics such as MOS to control pathogen growth by modulating the gut microbiome, and the applications of MOS as a nutritional supplement and as an alternative to antibiotics.

Funding Sources: Natural Sciences and Engineering Research Council of Canada