Structure of the major exopolysaccharide produced by Azotobacter beijerinckii B-1615

Abstract A. beijerinckii strain B-1615 produced two acidic exopolysaccharides in the ratio ∼9:1. The minor polysaccharide contained mannuronic and guluronic acids in the ratio 2.3:1 and is a bacterial alginate. The major polysaccharide consisted of d -galactose, l -rhamnose, and pyruvic acid in the ratios 2:1:1 and was acetylated. On the basis of methylation analysis, and 1 H- and 13 C-n.m.r. spectroscopy of the polysaccharide before and after removal of the pyruvic acid residues and O -deacetylation, it was concluded that the major polysaccharide had the structure with up to 1.5 OAc groups per repeating unit.