Lipid A in anaerobic bacteria.

The ability of lipid A preparations from strains of Bacteroides, Fusobacterium, and Veillonella to inhibit the lipid A-anti-lipid A reaction in an enzyme-linked immunosorbent assay was tested. Anti-lipid A serum was prepared with lipid A from Salmonella minnesota R595, and lipid A from Escherichia coli EH100 was used as control antigen. Preparations from three of four different species of Bacteroides were unable to inhibit the anti-lipid A activity, whereas lipid A preparations from Fusobacterium and Veillonella strains inhibited 50% of the activity at 1 to 141 micrograms. One of the Bacteroides strains, Bacteroides oralis, showed a very weak inhibiting activity at the highest concentration used. The results confirm that Bacteroides species have a unique lipopolysaccharide structure, in contrast to other anaerobic genera which have a lipopolysaccharide structure similar to that of the Enterobacteriaceae.