Lipopolysaccharides from six strains of Acetobacter diazotrophicus
Abstract
Lipopolysaccharides from six nitrogen-fixing strains of Acetobacter diazotrophicus (PR2, PAW, PALS, PR4, PR14, PR20), isolated from sugarcane, were purified by phenol-water extraction and ultracentrifugation. The relatively large molecular mass observed by SDS-PAGE indicated that the lipopolysaccharides of each strain possessed an O-side chain. Analysis of each lipopolysaccharide by calorimetric assays and by gas liquid chromatography/mass spectrometry combination showed that the core and lipid A composition was similar for all strains, containing 3-deoxy-D-manno-2-octulosonic acid, glucosamine and fatty acid (16-0, 3-OH-14, 2-OH-16:0, 3-OH-16:O). The neutral sugar composition showed the predominance of 6-deoxy-hexose (rhamnose and fucose) and ribose, in comparison with hexose (glucose, galactose, mannose). The presence of 6-deoxy-hexose and ribose containing O-side chains is discussed as a way of discriminating A. diazotrophicus from other Acetobacter species.