[Properties of polysaccharide complexes produced by Azospirillum brasilense and polysaccharides isolated from these...

Azospirillum brasilense strains Sp7, Sp7 (S-form), Sp107, Sp245, Sp246, S17, and 15 when cultivated in a liquid synthetic malate medium up to the end of the logarithmic phase of growth were shown to produce at least two complex polysaccharide-containing components. The components were arbitrarily called lipopolysaccharide-protein complex (LPPC) and polysaccharide-lipid complex (PSLC). The LPPCs and PSLCs from the strains Sp7, Sp107, Sp245, Sp246, and S17 were shown to interact with a wheat germ agglutinin (WGA). From PSLCs, acidic polysaccharides (PS) were isolated and their specific rotation, molecular masses, affinity for WGA, and monosaccharide composition were determined. The PSs of all strains contained rhamnose, galacturonic acid, and galactose (except the strain Sp246), and glucosamine (except the strain Sp7 (S-form)), while the PSs of the strains Sp7 and S17 also contained fucose and mannose, respectively. It is suggested that LPPCs and PSLCs may be involved in the process of interaction of azospirilla with wheat root surfaces, and that PSsare probably active parts of the LPPCs and PSLCs. The ability of LPPCs and PSs to interact with Congo red in aqueous solutions was investigated.