Capsular polysaccharides and lipopolysaccharides from two strains of Bacteroides fragilis

The capsular polysaccharide from Bacteroides fragilis strain NCTC 9343 contained six sugars: L-fucose, D-galactose, D- and L-quinovosamine, D-glucosamine, and galacturonic acid. The capsule of B. fragilis strain ATCC 23745 in addition contained D-glucose, L-fucosamine, L-rhamnosamine, and a 3-amino-3,6-dideoxyhexose, but lacked D-quinovosamine. The latter capsule also contained alanine (4%). The lipopolysaccharide of both strains contained the same sugars (L-rhamnose, D-glucose, D-galactose, and D-glucosamine) and fatty acids (13-methyltetradecanoic, 3-hydroxypentadecanoic as major constituents). The capsular polysaccharide of both strains promoted abscess formation, whereas the lipopolysaccharide failed to do so.