Structure of a polysaccharide from a Rhizobium species containing 2-deoxy-β-d-arabino-hexuronic acid Original Research Article

The structure of the extracellular polysaccharide (EPS) produced by the Rhizobium sp. B strain isolated from atypical nodules on alfalfa has been determined using a combination of chemical and physical techniques (methylation analysis, high pH-anion exchange chromatography (HPAEC), mass spectrometry and 1-D and 2-D NMR spectroscopy). As opposed to the EPS from other strains of Rhizobium, the EPS from the sp. B strain contains d-Glc together with l-Rha and 2-deoxy-d-arabino-hexuronic acid. It is a polymer of a repeating unit having the following structure:→4)-β-d-Glcp-(1→4)-α-l-Rhap-(1→3)-β-d-Glcp-(1→4)-2-deoxy-β-d-GlcpA-(1→The polysaccharide also contains 0.6 O-acetyl groups per sugar which have not been located.