A polysaccharide antigen from the Gram-positive organism Eubacterium saburreum containing dideoxyhexose as the immunodominant sugar.

A highly active surface antigen, reacting by precipitation and complement fixation, has been isolated from Eubacterium saburreum strain L32. The antigen is a polysaccharide polymer built up of galactose, ribose and dideoxyhexose. The dideoxyhexose is the immunodominant sugar.