Production of oligoglucuronans by enzymatic depolymerization of nascent glucuronan.

An original bioreactor process for production of oligoglucuronans was developed using the Sinorhizobium meliloti M5N1CS strain that produces glucuronan. This anionic homopolysaccharide was composed of beta-D-(1,4)-glucopyranosyluronic residues variably O-acetylated at C-3 and/or C-2 positions according to culture conditions. It was depolymerized during its biosynthesis by addition of a fungal glucuronan lyase activity in broths. After purification by tangential ultrafiltration and low-pressure liquid chromatography, (1)H NMR and ESI-Q/TOF-MS characterized the poly- and oligoglucuronic acid fractions. This enzymatic bioreactor strategy authorized the production in gram quantity of an unsaturated and no acetylated oligoglucuronan with a degree of polymerization of 3.