Structure of the repeating oligosaccharide from the lipopolysaccharide of the nitrogen-fixing bacterium Acetobacter diazotrophicus strain PAL 5

Acetobacter diazotrophicus is an acid-tolerant nitrogen-fixing bacterium found in roots, rhizosphere, stems, and leaves of sugar cane (Saccharum officinarum) cultivated in Brazil. The O-polysaccharide from the lipopolysaccharide of the root isolate strain PAL 5 has been determined by a combination of methylation analysis and two-dimensional high field NMR spectroscopy. The pentasaccharide repeat has the structure: Minor resonances in the NMR spectra are consistent with the presence of a proportion of repeating units which lack the β-d-Glc side-chain.