SOME RHEOLOGICAL PROPERTIES OF THE EXTRACELLULAR POLYSACCHARIDE PRODUCED BY VOLCANIELLA-EURIHALINA F2-7

Volcaniella eurihalina strain F2-7 synthesizes an exopolysaccharide named V2-7, primarily composed of glucose, mannose, and rhamnose. The effect of chemical and physical factors on solution viscosity was studied. The V2-7 EPS showed pseudoplastic behavior at concentrations over 0.5% W/V. Viscosity decreased with temperature, but the viscosity values were restored after cooling. Freeze-thawing treatment did not affect the theological properties of its solutions. Addition of inorganic salts produced a diminution of viscosity. However, the most remarkable aspect of V2-7 EPS is the effect of pH on its solutions; it is able to form high viscosity solutions, like a gel, at low pH values even in the presence of inorganic salts. This property, not present in neutral and alkaline solutions, makes it potentially useful for various industrial applications.