Growth Assessment of Bifidobacterium on Glucansucrase-Derived Oligosaccharides

Prebiotics are dietary supplements used to selectively stimulate the growth of beneficial intestinal bacteria such as Bifidobacterium in humans and animals. Maintenance of beneficial intestinal bacteria may provide ecological-based, health-promoting factors such as disease suppression and improved metabolism. A promising source of potential prebiotic supplements is through enzymatic synthesis of oligosaccharides using microbial glucansucrase enzymes. Glucansucrases can be used to prepare a seemingly endless variety of potential prebiotic oligosaccharides containing various linkage structures and monosaccharide components. In this study, six oligosaccharide products synthesized by bacterial glucansucrase were assessed for ability to support bacterial growth (growth rate, µ h^-1) and biomass (cell dry weight, mg ml^-1) formation using two Bifidobacterium species commonly associated with the gastrointestinal tract of animals. Each growth assessment was performed in triplicate and reported as the mean. Overall, oligosaccharide products Sucromalt (Cargill, Inc) and isomelezitose supported the highest growth rates for B. adolescentis (0.60, 0.69 µ h^-1) and B. pseudocatenulatum (0.66, 0.52 µ h^-1) when compared to glucose (0.51, 0.37 µ h^-1). The raffinose-derived and gentiobiose-derived oligosaccharide products supported the lowest growth rates for the listed species. In addition to growth rate, isomelezitose also supported the highest biomass formation for both Bifidobacterium species (497, 464 mg ml^-1) when compared to glucose and the other oligosaccharides. The raffinose-derived product, however, supported the second highest biomass formation for both species (404, 416 mg ml^-1) even though the growth rates were lowest indicating a slow but steady metabolism of this supplement by Bifidobacterium. In summary, the Sucromalt, isomelezitose, and raffinose products supported significant growth of intestinal Bifidobacterium and are good candidates for further studies of their prebiotic potential.