Structural analysis of the core oligosaccharides from Fusobacterium nucleatum lipopolysaccharides

Fusobacterium nucleatum is a gram-negative bacterium, part of the normal human microflora. It is associated with various health complications, including periodontitis and colorectal cancer. Its surface is covered with lipopolysaccharide, which interacts with the immune system and can be involved in various processes in health and disease conditions. Here we present the results of structural analysis of core oligosaccharides from the lipopolysaccharides of several strains of F. nucleatum. Pure compounds were isolated using mild acid hydrolysis or alkaline deacylation of the lipopolysaccharides and analyzed by NMR spectroscopy, mass-spectrometry and chemical methods. All cores analyzed had a common octasaccharide region, including five heptose residues and a non-phosphorylated 3-deoxy-d-manno-oct-2-ulosonic acid residue. The common region is substituted with different additional components specific for each strain. By structure type the F. nucleatum core is similar to that produced by Aeromonas.