Characterization of an acetan-like heteropolysaccharide produced by Kozakia baliensis NBRC 16680

Abstract

Kozakia baliensis NBRC 16680 produces a heteropolysaccharide (HePS), whose biosynthesis is similar to the biosynthesis of the exopolysaccharide acetan. To elucidate structural components and macromolecular properties of this HePS, we carried out methylation analysis, NMR spectroscopy, rheological measurements and size determinations. In accordance with acetan, the HePS are composed of 1,4-substituted Glcp, 1,3,4-substituted Glcp, 1,2-substituted Manp, 1,4-substituted GlcpA, and 1,6-substituted Glcp units. In contrast to acetan, rhamnose and acetylation of side chains were not detected. Furthermore, a putative, unidentified uronic acid and 1,6-substituted Galp units were found to be HePS constituents, both of which could not be correlated with the responsible HePS biosynthesis in contrast to the other present structural elements. Depending on the initial carbon source, K. baliensis HePS were produced in different amounts and exhibited different rheological properties and elution profiles during AF4 and HPSEC separations. In conclusion, we propose an acetan-like HePS with slight molecular weight variations depending on the production conditions.