Oligosaccharides-protein conjugates for selective targeting of proteins to probiotic bacteria in the colon
Abstract: ** Lecture will be given in English**
The human gut microbiome plays a central role in host health through its extensive interactions with host metabolism, immune function, and intestinal barrier integrity. Prebiotics are widely used to beneficially modulate the gut microbiota; however, currently available prebiotics are predominantly carbohydrate-based and do not address the limited availability of protein in the colon. Since approximately 90% of dietary proteins are digested and absorbed in the upper gastrointestinal tract, colonic microorganisms compete for residual unabsorbed peptides reaching the colon.
This research aimed to develop a next generation prebiotic platform: protein-containing prebiotics, designed to selectively deliver both prebiotic carbohydrates and protein substrate to gut probiotics, thereby enhancing their growth and beneficial metabolic activity relative to conventional carbohydrate-only prebiotics. To achieve this, Maillard conjugates composed of the prebiotic human milk oligosaccharide 2′-fucosyllactose (2′-FL) and protein peptic-then-tryptic hydrolysates were developed, forming self-assembled micellar structures with a protein core and an oligosaccharide shell. This structure retards upper gastrointestinal protein absorption, while aiming to enable oligosaccharide-mediated, selectively targeted delivery to colonic probiotics. The first proof-of-concept system, based on lactoferrin hydrolysates, significantly increased the abundance of short-chain fatty acid (SCFAs)-producing bacterial taxa, enhanced colonic SCFAs levels, and reduced plasma lipopolysaccharide levels in mice, demonstrating superior prebiotic efficacy and gut-barrier integrity promotion compared with unconjugated components and saline controls.
To improve scalability and sustainability, potato protein hydrolysates were subsequently evaluated as an alternative protein source. The resulting conjugates promoted health-associated bacterial taxa, enhanced microbial SCFAs production, and improved markers of gut barrier integrity and metabolic health in-vivo, outperforming conventional prebiotic and saline controls. These findings validate potato protein hydrolysates as a cost-effective, non-allergenic and sustainable alternative to lactoferrin hydrolysates. Importantly, no increase in harmful proteolytic fermentation byproducts was observed in either system. Finally, the platform was expanded into a multifunctional colonic delivery system, through the incorporation of the prebiotic polyphenol resveratrol into the conjugate assemblies, and their subsequent stabilization by genipin-mediated crosslinking. Crosslinking reduced proteolytic susceptibility and premature resveratrol release, supporting the feasibility of co-delivering prebiotic carbohydrates, peptides, and polyphenols to the colon within a single delivery vehicle, offering a novel strategy for enhanced beneficial modulation of the gut microbiota and promotion of gut and metabolic health.
Collectively, this work establishes protein-containing prebiotics as a novel strategy for targeted microbiome modulation and provides a versatile platform for the development of next-generation functional foods and gut- and metabolic-health interventions.
