Cytological Comparison of Spores of Different Strains of Bacillus Megaterium.

The content of the phosphorus fractions in bacillus spores reveal a marked difference in the quantity of residue phosphorus (Fitz-James and Young, 1959). In particular, the spores of two strains of Bacillus megaterium contained a residue phosphorus of over 1 per cent of the dry weight whereas in another strain it was essentially nil. This residue fraction remaining after a modified Schmidt and Thamnhauer extraction procedure (Fitz-James, 1955) is composed of spore coats, membranes, and some undigested acid-precipitated protein. Removal of the protein from these residues by re-extraction with alkali and of cell wall components by digestion with lysozyme did not alter the phosphorus content of the residue (Fitz-James, 1955). It thus appears that the phosphorus is associated with some insoluble component of the spore coats. This structural comparison of spores of strains of B. megaterium revealed that a high content of residue phosphorus is associated with the presence of a heavy outer spore coat and that this extra layer influences the behavior of the spores to staining procedures.