CONSTITUTION OF AN EXTRACELLULAR ACIDIC GLUCOMANNAN FROM SERRATIA MARCESCENS

Abstract

An acidic glucomannan isolated from culture filtrate of Serratia marcescens contained D-glucose and D-mannose (3.5:1), D-glucuronic acid (5.5%), and "bound" fatty acids (7.4%). The polysaccharide, on examination by moving boundary electrophoresis and by sedimentation in the ultracentrifuge, was homogeneous. Degree of polymerization was estimated to be ca. 20 by vapor pressure osmometry. Isolation of nigerose (3-O-α-D-glucopyranosyl-D-glucopyranose) established the glycosidic linkage between the D-glucose units as α (1 → 3). Methylation and periodate oxidation data showed that the D-glucose and D-mannose units were joined by (1 → 3) linkages in a straight chain structure terminated at the non-reducing end by a unit of D-glucuronic acid which was attached to C₃ of a D-mannose residue. The reducing end of the molecule was terminated by a D-glucose unit. The fatty acids, consisting mainly of hydroxymyristic acid and myristic acid, were attached to the molecule mainly by ester linkages.