An extracellular acid polysaccharide from Coelastrum sphaericum

An extracellular acid polysaccharide was precipitated at 70% ethanol, toget her with a mannose-containing carbohydrate, sucrose and glucose, from the c ulture media of Coelastrum sphaericum. Purification by repeated centrifugat ion and dialysis and gel permeation cromatography yielded a product compose d by an acid polysaccharide together with lesser amounts of a mannose-conta ining carbohydrate. Methylation analysis showed that the acid polysaccharid e had a linear backbone with an average structural unit formed by 3-linked L-rhamnopyranose (2 moles), 3-linked D-galactopyranose (1 mole), 3-linked D -glucopyranose (1 mole) and 4-linked D-glucopyranuronic acid (1 mole). The chain had L-rhamnopyranose (1.9 mol%) and D-galactofuranose (0.5 mol %) sin gle stubs 4-linked to the rhamnopyranose units in the backbone.