Isolation and characterization of an extracellular polysaccharide from Pseudomonas caryophylli CFR 1705.

A major exopolysaccharide produced during growth of Pseudomonas caryophylli CFR 1705 on lactose-containing medium was isolated and subjected to preliminary characterization. After purification by DEAE-cellulose chromatography, the polysaccharide was found to have a mol. wt. of 1.1 x 106 Da and contained rhamnose, mannose and glucose in respective proportions 1:3.26:4.97. GC MS after methylation demonstrated that the polysaccharide was a highly-branched 1,4-linked hexosan, containing glucose and mannose as branch-off residues and rhamnose as a non-reducing terminal residue.