The Chemical Composition of the Cytoplasmic Membrane of Bacillus subtilis

The cytoplasmic membrane of Bacillus subtilis 168, prepared from cells in the stationary phase, has been found to contain protein (62%), RNA (22%) and lipid (16%). Analyses of the membrane lipid revealed the presence of phospholipids (75%), neutral lipid (10%) and a compound identified as a diglucosyl diglyceride. The major phospholipids were diphosphatidyl glycerol and phosphatidyl ethanolamine, with small amounts of phosphatidyl glycerol and lipoamino acids. Branched chain fatty acids comprised over 75% of the total fatty acids of both whole cells and membranes. Iso and anteiso acids with 15 and 17 carbon atoms were the major components, together with small amounts of iso acids containing 14 and 16 carbon atoms and n ‐acids. No unsaturated acids were present.