Effects of organic solvents and inorganic salts on precipitation of extracellular polysaccharide from culture broth of Polianthes tuberosa callus

Abstract

Separation of extracellular polysaccharides (TPS) by precipitation from culture broth of Polianthes tuberosa callus was studied. Addition of water-miscible solvents (ethanol, acetone and 2-propanol) together with inorganic salts was effective for forming TPS precipitates. In the presence of 2% NaCl, the percentage of TPS precipitated from solution with dielectric constant of about 50 was nearly 100%, regardless of organic solvents added. In solution with 50 vol% ethanol, the molar ratio of cations in inorganic salts (Na+ and Ca2+) to glucuronic acid groups in TPS had a positive correlation with the percentage of TPS precipitated. Xanthan gum, which also contains the glucuronic acid group, showed similar precipitation properties to TPS under the conditions examined. The proposed method was effective for purifying TPS at an acceptable level without significant denaturing of TPS. © 2013 The Society of Chemical Engineers, Japan.