Characterization of the lipopolysaccharides from eight strains of the cyanobacterium Synechococcus

Lipopolysaccharides have been isolated from eight strains of the unicellular cyanobacterium Synechococcus. Fucose, mannose, galactose, glucose and glucosamine were found in all of the lipopolysaccharides investigated. Additionally, strain-specific sugars are present and permit the chemotyping of lipopolysaccharide. Chemotype I, comprising three strains with a high G+C content of DNA (71-66 mol%), is characterized by a high rhamnose portion and by 3,6-dideoxy-d-arabino-hexose (tyvelose). Chemotype III, represented by three strains with a low G+C content of DNA (55-48 mol%), contains a mannose-polymer with small amounts of 3-O-methyl-mannose, 4-O-methyl-mannose, 2-keto-3-deoxyoctonate and mannosamine. Lipopolysaccharides of the two strains of chemotype II contain 2,3,4-tri-O-methyl-arabinose.Lipid A is difficult to split off from the polysaccharide moiety, but is present in all lipopolysaccharides from the Synechococcus strains. The presence of Lipid A is supported by the finding of -hydroxy fatty acids, predominantly -hydroxypalmitic acid. The distribution of branched -hydroxy fatty acids, detected in small amounts, parallels chemotyping of lipopolysaccharide based on the sugar composition. The phosphorus content of the lipopolysaccharides is low.The pyrogenicity of lipopolysaccharides from two strains is low. Synechococcus lipopolysaccharides have little reactivity in antisera raised in rabbits against homologous cells. As far as tested they do not migrate in immunoelectrophoresis. This confirms the neutral character or low negative charge of Synechococcus lipopolysaccharides.Dedicated to Professor Otto Kandler on occasion of his 60th birthday