Structural characterization of the released polysaccharide of desiccation-tolerant Nostoc commune DRH-1

The structure of the viscous extracellular polysaccharide (glycan) of desic cation-tolerant Nosfoc commune DRH-1 was determined through chromatographic and spectroscopic methods. The polysaccharide is novel in that it possesse s a 1-4-linked xylogalactoglucan backbone with D-ribofuranose and 3-O-[(R)- 1-carboxyethyl] D-glucuronic acid (nosturonic acid) pendant groups. The pre sence of D-ribose and nosturonic acid as peripheral groups is unusual, and their potential roles in modulating the rheological properties of the glyca n are discussed. Nosturonic acid was present in the glycans of N, commune f rom diverse geographic locations, suggesting that this uronic acid is an in tegral component of this cosmopolitan anhydrophile.