Precipitating carbohydrate antigens of Bacteroides fragilis NCTC 9343.

An antigen fraction isolated by various forms of chromatography from phenol/water extracts of Bacteroides fragilis NCTC 9343 was devoid of phosphorus, fatty acids and amino acids. Rhamnose, fucose, galactose, glucose and a neutral sugar tentatively identified as arabinose were present at molar ratios of 1:1:1.2:9.0.9:0.7. The fraction contained an unidentified reducing and ninhydrin positive substance and trace amounts of glucosamine and galactosamine. The antigen fraction produced three immunoelectrophoretic bands against NCTC 9343 antiserum, and reacted in complement fixation tests.