Characterization of a new glycosaminoglycan-like exopolysaccharide produced by the marine bacterium Alteromonas macleodii Mo169

Marine microorganisms produce extracellular polysaccharides with unique features, such as the presence of unusual monosaccharides, adhesiveness to biotic and abiotic surfaces, and close similarity to glycosaminoglycans (GAG), that are of considerable interest for biotechnological applications. In the present study, an extracellular microbial polysaccharide (EPS) has been isolated and structurally characterized. The EPS producer is the Gram-negative bacterium Alteromonas macleodii Mo169, previously isolated from a marine environment in French Polynesia. The bacterium has been cultivated using glycerol as the sole carbon source. Interestingly, the secreted EPS was composed of 2-acetamido-2-deoxy-guluronic acid (GulNA) and 2-acetamido-2-deoxy-glucose (GlcN), two amino sugars not commonly found in the Alteromonas genus. The purified EPS, with a molecular weight of 0.30 ± 0.01 MDa, consisted of the following repeating unit: →4)-α-L-GulNAc3OAcA-(1 → 3)-β-D-GlcNAc-(1 →.