title: Heterogeneity in lipid composition of the outer membrane and cytoplasmic membrane and cytoplasmic membrane of Pseudomonas BAL-31.
abstract: The outer membranes and cytoplasmic membranes of the marine bacterium Pseudomonas BAL-31 were separated by washing the cells three times in 0.5 M NaCl and twice in 0.5 M sucrose. Electron microscopy during the removal of membranes revealed that the outer membranes fragmented in a regular manner to give rise to fairly uniform vesicles measuring approximately 140 nm in diameter. Isolated outer membranes had a buoyant density in sucrose of 1.230 g per cm(3), whereas the cytoplasmic membranes had a density of 1.194 g per cm(3). The removal of the outer membrane during the application of this procedure was monitored by measuring the release of 2-keto-3-deoxyoctulosonic acid and phospholipid. The cells lost 85.5% of their 2-keto-3-deoxyoctulosonic acid and 47.3% of their phospholipid during this treatment. Complete recovery of outer membrane material could be achieved. The removal of 25.5% of the 2-keto-3-deoxyoctulosonic acid and 0.9% of the phospholipid rendered the cells sensitive to lysis with Triton X-100. The phospholipid composition of the outer membrane was calculated to be 78.9% phosphatidylethanolamine and 16.1% phosphatidylglycerol. The phospholipid composition of the cytoplasmic membrane proved to be 71.5% phosphatidylethanolamine and 23.5% phosphatidylglycerol. The fatty acid composition was also found to be quantitatively heterogeneous between the two membranes.
mesh_terms: D001345:Autoradiography; D002462:Cell Membrane / Q000032:analysis*; D002473:Cell Wall / Q000032:analysis*; D002855:Chromatography, Thin Layer; D003470:Culture Media; D004352:Drug Resistance, Microbial; D005227:Fatty Acids / Q000032:analysis; D007651:Keto Acids / Q000032:analysis; D008055:Lipids / Q000032:analysis*; D008854:Microscopy, Electron; D010714:Phosphatidylethanolamines / Q000032:analysis; D010743:Phospholipids / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010761:Phosphorus Radioisotopes; D011549:Pseudomonas / Q000032:analysis* / Q000187:drug effects; D012623:Seawater; D012965:Sodium Chloride; D013395:Sucrose; D013501:Surface-Active Agents / Q000494:pharmacology; D014871:Water Microbiology
chemical_list: D003470:Culture Media; D005227:Fatty Acids; D007651:Keto Acids; D008055:Lipids; D010714:Phosphatidylethanolamines; D010743:Phospholipids; D010761:Phosphorus Radioisotopes; D013501:Surface-Active Agents; D010758:Phosphorus; D012965:Sodium Chloride; D013395:Sucrose