Production and purification of an extracellular polyglucan produced byCellulomonas flavigena strain KU

Abstract

A polysaccharide is synthesized byCellulomonas flavigena strain KU when it is cultured in a synthetic medium which uses ammonium salts as a nitrogen source and contains an excess of a carbon and energy source. Production of the polysaccharide begins in late log phase and reaches a maximimum during stationary phase. In batch cultures it may be produced in yields of up to 9 g dry polysaccharide/liter of culture. It is not secreted into the growth medium but rather remains associated with the cells, resulting, apparently, in their aggregation. When such aggregated cells are extracted with dilute sodium hydroxide solutions the polysaccharide is solubilized. Neutralization of supernatant fluid of such extracts results in sedimentation of the polysaccharide which may then be purified by extensive washing with water. The polysaccharide is insoluble in water, alcohols or acetone, but dissolves in concentrated formic acid, dimethyl-sulfoxide, and dilute sodiumor potassium hydroxide. Thin-layer and gas-liquid chromatographic analysis of hydrolysates indicated that it is a polyglucan. When resuspended in water at concentrations of 2–3% it forms a stable hydrogel.