Cyanospira capsdata, a heterocystous cyanobacterium isolated' from Magadi lake (Kenya) in 1982, synthesises an exocellular polysaccharide. Some compositional data on this macromolecule, together with its production under laboratory conditions and its isolation from the bacterial slime, have been reported2. A better characterisation of this hydrocolloid became desirable in view of its interesting rheological properties3.
We now report preliminary results on the purification, composition, and structure of the polysaccharide.
The crude polysaccharide contained4 6% of protein; when an aqueous solution was kept for 1 h at 100" and then centrifuged, the protein content of the material in the supernatant solution was reduced to 2%. This figure remained constant on further treatment with isoamyl alcohol-chloroform or after gel-filtration chromatography on Sephadex G-100. The presence of proteins in purified preparations of the polysaccharide was confirmed by polyacrylamide gel electrophoresis with sodium dodecyl sulphate, which showed a broad major band with M, 66,000 and minor bands of lower M,. The association of proteins or peptides with several polysaccharides has been reported 5,6, together with some indications in favour of a functional and structural role for these components.