STRUCTURAL STUDIES OF THE RHIZOBIUM-TRIFOLII EXTRACELLULAR POLYSACCHARIDE

The structure of the extracellular polysaccharide of Rhizobium trifolii has been investigated. Methylation analysis, sequential degradations by oxidation and elimination of oxidized residues, uronic acid degradation, and degradation by oxidation of the acetylated polysaccharide with chromium trioxide in acetic acid were the main methods used. It is proposed that the polysaccharide is composed of heptasaccharide repeating-units having the following structure: {A figure is presented} An unusual feature is that some of the repeating units are incomplete and lack the terminal β-d-galactopyranosyl group. The polysaccharide contains O-acetyl groups (somewhat more than 1 mol. per unit), linked to O-2 and O-3 of 4-O-substituted d-glucopyranosyl chain-residues. A previous finding that the polysaccharide contains 2-deoxy-d-arabino-hexose (2-deoxy-d-glucose) residues is erroneous. © 1979.