Biochemical and biological studies on the lipopolysaccharide of Bacteroides nodosus

Lipopolysaccharides (LPS) were extracted from three Bacteroides nodosus isolates by the aqueous phenol method and purified by ultracentrifugation. The structure of B nodosus LPS appears to be similar to enterobacterial LPS, with the polysaccharide component joined to the lipid A moiety through an acid-labile 2-keto-3-deoxyoctonic acid (KDO) linkage. B nodosus LPS contained glucose, galactose, hexosamine, KDO and heptose and no sugars apart from ribose, which was possibly a nucleic acid contaminant, were unique to any of the isolates. Electron microscopic examination indicated a similar morphology to LPS derived from other Gram-negative bacteria. B nodosus LPS was found to exhibit biological properties characteristic of endotoxins, such as pyrogenicity, leucopenic and leucocytotic activity, production of the primary inflammatory response in rabbit skin and Shwartzman reactivity. However, the toxicity of B nodosus LPS was low.