Bifidobacterium longum subsp. infantis carbohydrate transporters and glycosyl hydrolases (B. infantis HMO utilization system)

Bifidobacterium longum subsp. infantis (B. infantis) carbohydrate transporters and glycosyl hydrolases constitute a specialized metabolic system evolved to utilize human milk oligosaccharides (HMOs). This system includes a variety of ATP-binding cassette (ABC) transporters and intracellular glycoside hydrolases—such as sialidases, fucosidases, and hexosaminidases—that allow the bacterium to internalize and degrade complex glycans found in breast milk (Sela et al., 2008, PNAS). By efficiently sequestering these nutrients, B. infantis outcompetes potential pathogens in the infant gut, such as Enterobacteriaceae, thereby promoting a healthy microbiome (Garrido et al., 2011, Food Microbiology). This metabolic pathway is a primary target for synbiotic therapies, where specific HMOs (prebiotics) are administered to selectively support the growth of B. infantis (probiotic) (Henrick et al., 2018, mSphere). Clinical applications focus on preventing necrotizing enterocolitis, reducing systemic inflammation, and restoring gut health in infants with dysbiosis (Underwood et al., 2013, Pediatric Research).

Other names

HMO utilization clusterB. infantis carbohydrate metabolism systemH5 gene clusterHuman milk oligosaccharide utilization machinery

Selective fermentation of human milk oligosaccharides (HMOs) by B. infantis leads to the production of lactate and acetate, lowering intestinal pH and inhibiting the growth of pH-sensitive pathogens while promoting gut barrier integrity.