Structural determination and NMR characterization of a bacterial exopolysaccharide

A strain of Bacillus licheniformis with high exopolysaccharide (EPS) production ability was isolated and identified. A new type of EPS was isolated from the strain fermentation and its structural characteristics were investigated and elucidated by partial and total acid hydrolysis, Fourier transform infrared, and 1H and 13C NMR spectroscopy including 2D 1H, COSY, NOESY, XHCOR and HMBC experiments. Based on obtained data, the EPS was found to be a levan composed of linear chains of (2 → 6)-linked β-d-fructofuranosyl residues with connections β (2 → 6).