In Vitro Fermentation of Arabinoxylan-Derived Carbohydrates by Bifidobacteria and Mixed Fecal Microbiota

Abstract

Bifidobacterium adolescentis ATCC 15703, Bifidobacterium breve ATCC 15700, Bifidobacterium longum ATCC 15707, and human fecal microbiota were cultivated in vitro with d-xylose, l-arabinose, xylo-oligosaccharides (XOS), and arabinoxylo-oligosaccharides (AXOS) as carbon sources. The pH, formation of volatile fatty acids, and carbohydrate utilization profiles were followed. In the pure bifidobacteria cultures optical density and in the fecal slurries pressure and H(2) were also detected. A differing substrate preference was observed among the various bifidobacteria strains. B. adolescentis grew on XOS, slowly on d-xylose, but not on l-arabinose. In contrast, B. longum preferred l-arabinose and did not grow on pure d-xylose or XOS. Both strains were able to utilize AXOS but with differing strategies, since after the cleavage of l-arabinose B. adolescentis consumed the XOS formed, whereas B. longum fermented the l-arabinose released. B. breve grew poorly on all of the substrates provided. A bifidobacterial mixture and the fecal microbiota were able to utilize pure singly substituted AXOS almost completely, but pure AXOS with a doubly substituted xylose residue was fermented only by the fecal microbiota. Thus, AXOS appear to be potential candidates for slowly fermenting prebiotics, but their prebiotic effects may be dependent on the type of arabinose substitution and the presence of other carbohydrates.

Characterization of a Novel β-l-Arabinofuranosidase in Bifidobacterium longum

“…B. longum JCM 1217 encodes a number of candidates for the ␣-L-arabinofuranosidase gene, 11 members of the GH43 gene family, and 4 members of the GH51 gene family. Several reports indicate that B. longum has the ability to grow on L-arabinose and ␣-L-arabinooligosaccharides (14,23,(25)(26)(27). We showed that B. longum also uses ␤-Ara 2 as a carbohydrate source (supplemental Table S4).…”

A Human Gut Commensal Ferments Cranberry Carbohydrates To Produce Formate

“…Importantly, B. longum subsp. longum ATCC 15707 does not grow on xylose but metabolizes arabinose as a sole carbohydrate source (36). Accordingly, B. longum subsp.…”

The Ability of Bifidobacteria To Degrade Arabinoxylan Oligosaccharide Constituents and Derived Oligosaccharides Is Strain Dependent

“…This is in contrast with the finding that these strains contained several intracellular ␣-arabinofuranosidase genes, which indicates transport of AXOS into the cell and subsequent intracellular degradation. Extracellular arabinose substituent cleavage has been reported for B. longum VTT E-96664 and B. longum VTT E-96702 when grown on AX (16) and for B. adolescentis ATCC 15703 and B. longum ATCC 15707 when grown on AXOS (17), albeit based on endpoint determinations or making use of purified shortchain AXOS standards, respectively. Although the extracellular cleavage of arabinose substituents by cluster II and IV strains suggests the presence of extracellular ␣-arabinofuranosidases, no such enzymes have been characterized in B. longum until now (11,37).…”

“…Until now, studies of the degradation of AXOS and AX through monoculture fermentations with bifidobacterial strains have been restricted to the monitoring of bacterial growth, pH, and SCFA production (15,16). Also, fermentations of purified short-chain AXOS standards have been performed (17). However, these studies do not reveal the complete fermentation capacity of bifidobacteria.…”