Physicochemical analyses of the exopolysaccharides produced by a marine biofouling bacterium, Vibrio alginolyticus

Growth and exopolysaccharide (EPS) production by Vibrio alginolyticus, a marine fouling bacterium was studied in sea water nutrient broth in vitro. Fourier transformed infrared spectral analysis of the purified EPS revealed prominent characteristic groups corresponding to polyhydric alcohols. When the derivatized alditol acetates from EPS were separated by gas chromatography five peaks corresponding to glucose tetraacetate, xylopyranose tetraacetate, aminoarabinose tetraacetate, aminoribose tetraacetate and glucose pentaacetate, were observed. Mass spectrophotometric analysis of derivatized EPS revealed the presence of glucose, aminoarabinose, aminoribose and xylose in the molar ratio of 2:1:9:1. Viscometric studies suggested that the molecular weight of EPS was similar to 6.39 x 10(6) Da. Rheological studies of aqueous EPS showed good shearing property. However, the EPS was unstable at high temperatures and high pH. (C) 2002 Elsevier Science Ltd. All rights reserved.