Lipopolysaccharides of Rhizobium

Hot phenol-water extractions were carried out of cells from 12 strains of the fast-growing rhizobia Rhizobium leguminosarum, Rhizobium phaseoli, Rhizobium trifolii and Rhizobium meliloti. Purified lipopolysaccharide preparations contain neutral sugars, hexosamines, 2-keto-3-deoxyoctonate and uronic acids. Glucose, galactose, mannose, rhamnose and fucose are present in the majority of the LPS-preparations, but in varying proportions. Heptose was only found in some of them. O-methylated sugars are present in small amounts is most preparations, the kind of sugar being characteristic for lipopolysaccharides from different species. The lipid A part of lipopolysaccharides from all strains examined has identical patterns of fatty acids, namely -OH-C_14:0, -OH-C_15:0 (anteiso branched), -OH-C_16:0 and -OH-C_18:0. Comparison of the total compositions of Rhizobium lipopolysaccharides shows many differences among different species as among strains of a single species. Nearly identical lipopolysaccharide compositions also exist among certain strains, which constitute the same chemotype and which are also immunologically related. In view of a possible role of surface carbohydrates of Rhizobium in the root nodule symbiosis, the specificity of the binding of legume lectins with exo- and lipopolysaccharides of Rhizobium is discussed.Non-Standard Abbreviations LPS lipopolysaccharide(s) - EPS exopolysaccharides(s) - cetavlon cetyltrimethylammoniumbromide - KDO 2-keto-3-deoxyoctonate - ECL equivalent chain length Part II on Surface Carbohydrates of Rhizobium