Structure of simusan, a new acidic exopolysaccharide from Arthrobacter sp.

Simusan, a major exopolysaccharide produced by an ethanol-utilizing Arthrobacter sp. strain CE-17, contains d-glucose, d-mannose, d-galactose, l-rhamnose, d-glucuronic acid, and pyruvic acid in the ratios ∼ 3:2:1:1:1:1 as well as O-acyl groups (presumably residues of acetic and palmitic acid). On the basis of chemical modifications of the polysaccharide, solvolysis with anhydrous hydrogen fluoride resulting in a penta- and an octa-saccharide fragment, Smith degradation, and 1H and 13C NMR analysis, the following structure of the repeating unit was established: It is suggested that at least one of the glucose residues and the galactose residue are O-acetylated.