Extracellular polysaccharide-containing complexes and polysaccharides fromthe bacterium Azospirillum brasilense Cd

Two types of polysaccharide-containing biopolymers, conventionally termed l ipopolysaccharide-protein complexes (LPPCs) and polysaccharide-lipid comple xes (PSLCs), were isolated from the culture liquid and surface Azospirillum brasilense Cd cells grown to the end of the exponential phase in liquid ma late-containing medium. LPPCs differed from PSLCs by the molecular mass, fa tty acid composition of lipid components, and contents of carbohydrates, pr oteins, and 2-keto-3-deoxyoctulosonic acid. LPPCs, PSLCs, and polysaccharid es obtained by PSLC degradation contained N-acetyl-D-glucosamine (GlcNAc), the specific hapten of wheat germ agglutinin (WGA). The isolated polysaccha ride-containing complexes and polysaccharides inhibited WGA activity in the reaction of hemagglutination. The low-molecular-weight fraction of the cap sular polysaccharide-containing complexes contained free polysaccharide spe cifically interacting with WGA. As demonstrated by the slide technique, tre atment with LPPCs and PSLCs significantly increased the number of deformed root hairs on roots of two-day-old wheat seedlings. It was concluded that p olysaccharide-containing complexes produced by young A. brasilense Cd cultu res are involved in the interaction of these bacteria with wheat roots.