Structural Investigation of the Capsular Polysaccharide Produced by Cryptococcus Isolated from Sea Water

Abstract

Cryptococcus No.7 strain, isolated from sea water, produced a extracellular polysaccharide when grown on media containing sucrose. Purification of the polysaccharide has been accomplished by precipitation with Cetavlon and ethyl alcohol. Purified polysaccharide gave a homogeneous peak in Sepharose 4B column chromatography. Homogeneity of this substance also confirmed by ultracentrifugal analysis and electrophoresis, Chemical analyses showed the absence of aminosugar, amino acid, and protein.
Preliminary structural studies on the polysaccharide suggest that it consists of the eight saccharide repeating unit having xylose, mannose, and glucuronic residues, in the ratio of 3: 3: 2, to which must be added O-acetyl group. Two units of 3-O-(glucopyranosyluronic acid) xylose are present as side chains, and these glucuronic acid residues occur as the terminal end groups. Two residues of (1, 2, 3) linked mannose must be branching points in the main chain.