In vitrogrowth of four individual human gut bacteria on oligosaccharides produced by chemoenzymatic synthesis

The present study aimed at examining oligosaccharides (OS) for potential stimulation of probiotic bacteria. Nineteen structurally well-defined candidate OS covering groups of beta -glucosides, alpha -glucosides and alpha -galactosides with degree of polymerization 2-4 were prepared in >100 mg amounts by chemoenzymatic synthesis (i.e.reverse phosphorolysis or transglycosylation). Fourteen of the OS are not naturally occurring and five ( beta -d-glucosyl-fructose, beta -d-glucosyl-xylitol, alpha -glucosyl-(1,4)-d-mannose, alpha -glucosyl-(1,4)-d-xylose; alpha -glucosyl-(1,4)-l-fucose) have recently been synthesized for the first time. These OS have not been previously tested for effects of bacterial growth and here the ability of all 19 OS to support growth of four gastrointestinal bacteria: three probiotic bacteria Bifidobacterium lactis, Bifidobacterium longum, and Lactobacillus acidophilus, and one commensal bacterium, Bacteroides vulgatushas been evaluated in monocultures. The disaccharides beta -d-glucosyl-xylitol and beta -d-glucosyl-(1,4)-xylose noticeably stimulated growth yields of L. acidophilusNCFM, and additionally, beta -d-glucosyl-(1,4)-xylose stimulated B. longumBl-05. alpha -Glucosyl-(1,4)-glucosamine and alpha -glucosyl-(1,4)-N-acetyl-glucosamine enhanced the growth rate of B. animalissubsp. lactisand B. longumBl-05, whereas L. acidophilusNCFM and Bac. vulgatusdid not grow on these OS. alpha -Galactosyl-(1,6)- alpha -galactosyl-(1,6)-glucose advanced the growth rate of B. animalissubsp. lactisand L. acidophilusNCFM. Thus several of the structurally well-defined OS supported growth of beneficial gut bacteria. This reflects a broad specificity of their sugar transporters for OS, including specificity for non-naturally occurring OS, hence showing promise for design of novel prebiotics.