Isolation and purification of cell wall polysaccharide of Bacillus anthracis (Δ Sterne)

A polysaccharide fraction was isolated form sodium-dodecyl-sulfate (SDS) treated cell walls of Bacillus anthracis (delta Sterne) by hydrofluoric acid (HF) hydrolysis and ethanolic precipitation. The polysaccharide fraction was subsequently purified by several washings with absolute ethanol. Purity of the isolated polysaccharide was tested using the anthrone assay and amino acid analyzer. The molecular mass of the polysaccharide fraction as determined by gel filtration chromatography was about 12000 Da. Preliminary analyses of the polysaccharide was done using thin layer chromatography and amino acid analyzer, and results obtained from these analyses were further confirmed by gas liquid chromatography and 13C-NMR spectroscopy. Results showed that the polysaccharide moiety contained galactose, N-acetylglucosamine, and N-acetylmannosamine in an approximate molar ratio of 3:2:1. This moiety was devoid of muramic acid, alanine, diaminopimelic acid, glutamic acid, and lipid, thus indicating that the isolated polysaccharide was of pure quality.