Walls of Bacillus megaterium NCIB 7581 consisted principally of peptidoglycan (55%, w/w) and a single acidic carbohydrate accessory polymer (about 30%, w/w), which was isolated from lysozyme-digests of the walls. Glucose and N-acetylglucosamine partly made up this polymer, but phosphate and uronic or aminouronic acids were absent from the polymer and the wall. Protein (about 10%, w/w) was present in the walls, even though incubation with trypsin was a step in their isolation. When released into solution, this protein gave a single band on gel-electrophoresis and could be digested by trypsin. The remainder of the material isolated as walls was poly β-hydroxybutyrate, which represented cytoplasmic contamination. Capsules were formed best by bacteria on solid media containing amino acids, at relatively low growth temperatures. The isolated capsular material was polypeptide.
A polysaccharide of molecular mass at least 300000 Da was isolated from walls of Bacillus megaterium NCIB 7581. Three sugars, N-lactyl-3-amino-3,6-dideoxyhexose, N-acetylglucosamine and glucose were present in equimolar proportions, and accounted for 90% of the carbon of the polysaccharide. The remainder of the polymer was an unidentified acidic molecule, with a hydrophobic nature.