Structure characterization of a fucose-containing exopolysaccharide produced by Enterobacter cloacae Z0206

A novel high molecular weight (1.1 × 106 Da) exopolysaccharide (EPS) produced by Enterobacter cloacae Z0206 strain was isolated by column chromatography. Complete hydrolysis of the EPS followed by gas chromatography mass spectrometry (GC–MS) and high performance liquid chromatography (HPLC) analyses showed that the EPS is composed of l-fucose, d-glucose, d-galactose, d-glucuronic acid and pyruvic acid in the approximate molar ratio of 2:1:3:1:1. Partial acid hydrolysis of the purified EPS followed by gel permeation chromatography (GPC) yielded a hexasaccharide. A combination of chemical analysis coupled with mass spectrometry and 1D and 2D NMR spectroscopy applied to the oligosaccharide showed that the EPS comprises a heptasaccharide repeating unit.