Carbohydrate catabolic diversity of bifidobacteria and lactobacilli of human origin

Because increased proportions of particular commensal bacteria such as bifidobacteria and lactobacilli have been linked to human health through a variety of mechanisms, there is corresponding interest in identifying carbohydrates that promote growth and metabolic activity of these bacteria. We evaluated the ability of 20 carbohydrates, including several commercially available carbohydrates that are sold as prebiotic ingredients, to support growth of 32 human-derived isolates belonging to the genera Bifidobacterium and Lactobacillus, including those isolated from healthy elderly subjects. In general, bifidobacterial strains were shown to display more diverse carbohydrate utilization profiles compared to the tested Lactobacillus species, with several bifidobacterial strains capable of metabolizing xylo-oligosaccharide (XOS), arabinoxylan, maltodextrin, galactan and carbohydrates containing fructo-oligosaccharide (FOS) components. In contrast, maltodextrin, galactan, arabinogalactan and galactomannan did not support robust growth (≥0.8 OD_600nm) of any of the Lactobacillus strains assessed. Carbohydrate fermentation was variable among strains tested of the same species for both genera. This study advances our knowledge of polysaccharide utilization by human gut commensals, and provides information for the rational design of selective prebiotic food ingredients.