Structural elucidation of the capsular polysaccharide of Bacteroides fragilis strain 23745M1

The capsule of Bacteroides fragilis (ATCC23745) consists of two distinct polysaccharides, the separation of which could not be accomplished. The mouse-passaged strain (23745M1), however, yielded a preponderant polysaccharide which was isolated and purified. Using mainly high resolution NMR spectroscopy, the structure of the polysaccharide was elucidated and it is composed of the following repeating unit: where α-l-d-Yer is 3,6 dideoxy-4-C-(l-glycero-4′-hydroxyethyl)-α-d-xylo-hexopyranoside.