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.