Simultaneous production of two different gel-forming exopolysaccharides by an Alteromonas strain originating from deep sea hydrothermal vents

• Published in: Carbohydrate polymers 1997-12, Vol.34 (4), p.235-241
• Main Authors: Samain, E., Miles, M., Bozzi, L., Dubreucq, G., Rinaudo, M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacteria; Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; Dialysis; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gels; Methods. Procedures. Technologies; Natural polymers; Physicochemistry of polymers; Rheology; Starch and polysaccharides; Viscosity of liquids
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/S0144-8617(97)00129-X

Exopolysaccharide production by the marine bacterium Alteromonas sp. strain 1644 was shown to be stimulated by restricted growth conditions and was optimized in nitrogen limited fed-batch cultures. Exopolysaccharides were either partly secreted in the medium or stayed firmly cell-associated. The cell-polysaccharide associations could be destroyed by dialysis against distilled water, allowing polysaccharide purification. The chemical and rheological characterization of this last polysaccharide showed that it was different from the secreted polysaccharide that has been previously described (polysaccharide 1644). At low ionic concentration (below 0.03 M whatever the nature of the ions), solutions of this new polysaccharide had very low viscosities. However, at higher ionic concentration, it formed a gel or exhibited in solution at low polymer concentration an unusually high temperature dependent viscosity. This behaviour was also dependent on the nature of the ions and the following sequences for cations and anions were NH4 + > Mg 2+ > Na + > Li + > K + > TMA + and Br − > NO 3 − > SO 4 2− > Cl − > I − respectively.