1. 1. The lipid composition in cells of Bifidobacterium bifidum var. pennsylvanicus grown with and without human milk was determined so that the effect on lipids of cell wall inhibition in the absence of human milk might be assessed. The carbohydrate content in whole cell, membrane and cytoplasmic lipids was considerably decreased after cell wall inhibition. The phosphorus content showed a minor decrease. 2. 2. These alterations were not due to the lower acidity arising in the medium during growth without human milk. 3. Eighteen phospholipids were detected. Diphosphatidyl glycerol, phosphatidyl glycerol and an unidentified compound were the major phospholipids. Mono-, di-and triacyl-bis-(glycerophosphoryl)glycerol, alanyl phosphatidyl glycerol, and phosphatidic acid were present in smaller quantities. 3. 4. After cell wall inhibition the amount of triacyl-bis-(glycerophosphoryl)-glycerol was increased considerably. Phosphatidyl glycerol and two unidentified phospholipids were decreased, but diphosphatidyl glycerol remained constant. 4. 5. The decrease of phosphatidyl glycerol, and to a lesser extent triacyl-bis-(glycerophosphoryl)glycerol, were a response upon exposure to a medium of lower acidity. 5. 6. All glycolipids were galactolipids. Besides mono-, di- and trigalactosyldigly-ceride, a monoacyl- and a diacyi derivative of monogalactosyldiglyceride, and a monoacyl derivative of digalactosyldiglyceride were detected. Monogalactosyl- and digalactosylmonoglyceride were present in very small amounts. 6. 7. A proline-containing lipid without phosphorus was detected. © 1969.
