LIPOPOLYSACCHARIDES FROM 6 STRAINS OF ACETOBACTER-DIAZOTROPHICUS

Lipopolysaccharides from six nitrogen-fixing strains of Acetobacter di azotrophicus (PR2, PAL3, PAL5, PR4, PR14, PR20), isolated from sugarca ne, were purified by phenol-water extraction and ultracentrifugation. The relatively large molecular mass observed by SDS-PAGE indicated tha t the lipopolysaccharides of each strain possessed an O-side chain. An alysis of each lipopolysaccharide by colorimetric assays and by gas li quid chromatography/mass spectrometry combination showed that the core and lipid A composition was similar for all strains, containing 3-deo xy-D-manno-2-octulosonic acid, alucosamine and fatty acid (16-0, 3-OH- 14, 2-OH-16:0, 3-OH-16:0). The neutral sugar composition showed the pr edominance of 6-deoxy-hexose (rhamnose and fucose) and ribose, in comp arison with hexose (glucose, galactose, mannose), The presence of B-de oxy-hexose and ribose containing O-side chains is discussed as a way o f discriminating A. diazotrophicus from other Acetobacter species.