ISOLATION, FRACTIONATION AND SOME PROPERTIES OF POLYSACCHARIDES PRODUCED IN A BOUND FORM BY AZOSPIRILLUM-BRASILENSE AND THEIR POSSIBLE INVOLVEMENT IN AZOSPIRILLUM-WHEAT ROOT INTERACTIONS

It was shown that Azospirillum brasilense strains Sp7, Sp107, Sp245, and S17 when cultivated in a liquid synthetic malate medium to the end of the exponential phase of growth, produced at least two complex polysaccharide-containing components. The components were arbitrarily called lipopolysaccharide-protein complex and polysaccharide-lipid complex. These complexes were shown to interact with a wheat germ agglutinin. From polysaccharide-lipid complexes, acidic polysaccharides were isolated and their specific rotation, molecular masses, affinity for wheat germ agglutinin, and monosaccharide composition were determined. The polysaccharides of all strains contained rhamnose, galacturonic acid, and glucosamine, while the polysaccharides of strains Sp7 and S17 included additional fucose and mannose, respectively, and both had galactose. It is suggested that lipopolysaccharide-protein complexes, polysaccharide-lipid complexes, and polysaccharides may be involved in the process of interaction of azospirilla with wheat root surfaces.