Oligosaccharide-lactoferrin shell-crosslinked particles for selective targeting of proteins to probiotic bacteria in the colon

Abstract

Consumption of prebiotics seems to be a more effective approach for improving health compared to consumption of probiotic bacteria. However, these beneficial microorganisms require proteins to proliferate, while most consumed protein does not reach the gut. Still, no protein-containing prebiotics are commercially-available. Probiotic bacteria express sugar-binding-proteins (SBP) on their cell-membrane that mediate uptake of prebiotic oligosaccharides (OS). We have recently shown that Galactooligosaccharide-Lactoferrin hydrolysate (GOS-LFH) Maillard conjugates can serve as a vehicle for targeted delivery of protein to a model probiotic bacterium (Lactobacillus casei), boosting its growth rate. Herein, we aimed to advance this targeted protein delivery system by preparing three different compositions of prebiotic OS-LFH (2′-Fucosyllactose-LFH (2′-FL-LFH), Fructooligosaccharide-LFH (FOS-LFH), and Xylooligosaccharide-LFH (XOS-LFH)) self-assembled micellar particles, and characterizing their structure, physicochemical properties, and in-vitro digestibility. The OS shell of the particles is the molecular-recognition ligand for selective targeting to probiotic's SBP, and a shield against premature digestion of the delivered protein. We have demonstrated that these OS-LFH conjugates self-assembled into 10–25 nm particles, exhibiting good colloidal stability and lower susceptibility to proteolysis compared to the native lactoferrin (LF). Shell-crosslinking significantly reduced in-vitro gastrointestinal digestibility of the protein core. The proteolysis of the crosslinked 2′-FL-LFH, FOS-LFH, XOS-LFH progressed to only 55%, 57%, and 68% respectively, compared to native LF. Collectively, our findings suggest that these OS-LFH particles embody a promising strategy for high endurance and selective targeted delivery of protein to gut probiotics, which may enhance their competitive edge over non-beneficial/harmful colon bacteria, thereby promoting their potential to improve health.