On the amino acid esters of phosphatidyl glycerol from bacteria

1. 1. The phospholipids of Staphylococcus aureus were fractionated on silicic acid columns. The major compounds all appeared to be polyglycerol lipids. Diphosphatidyl glycerol and phosphatidyl glycerol were identified by comparison with the synthetic phospholipids. 2. 2. An amino acid derivative of phosphatidyl glycerol was isolated in pure form and shown to be identical with an -lysine ester of 1,2-diacyl-glycero-3-phosphoryl-I′-glycerol. 3. 3. The content and composition of phospholipids of Staphylococcus aureus were found to depend on the pH of the medium. In cells harvested at pH 7.0 phosphatidyl glycerol was the major phospholipid, whereas the lysine ester of phosphatidyl glycerol appeared to prevail below pH 5. Under certain conditions a relative increase in diphosphatidyl glycerol was observed. These alterations in the phospholipid pattern of the bacterial culture were reversible. 4. 4. Cells of Streptococcus faecalis manifested a comparable shift in the ratio of phosphatidyl glycerol and its lysine ester, but not all bacterial species studied responded in a similar way upon exposure to an acidic environment