Partial characterization of the lipopolysaccharides of peanut specific Bradyrhizobium strains

Hexoses, heptose, hexuronic acids, 2-keto-3-deoxyoctonic acid (Kdo) contents of the lipopolysaccharides (LPS) isolated from peanut (A. hypogaea) specific Bradyrhizobium strains NC 92, IGR 92, IGR 40 and IGR 6 were found to vary considerably. Sodium dodecyl sulphate polyacrylamide gel electrophoresis showed a heterogeneous LPS population and distinct heterogeneity was observed in NC and IGR strains. Sepharose gel filtration chromatography removed the hexose contaminants from NC 92 LPS. Polysaccharides obtained by mild acid hydrolysis of Sepharose purified NC 92 LPS were further purified on Sephadex G-50 gel filtration. Immunoblot analysis indicated cross reactivity amongst the peanut specific Bradyrhizohium strains but not with B. japonicum(SB 16). Antibodies raised against native NC 92 LPS showed higher binding towards the Sephadex purified polysaccharides suggesting the antigenic property of polysaccharide moiety in LPS molecule.