Heterogeneity in lipid composition of the outer membrane and cytoplasmic membrane and cytoplasmic membrane of Pseudomonas BAL-31

• Published in: Journal of bacteriology 1974-09, Vol.119 (3), p.1006-1018
• Main Authors: Diedrich, D L, Cota-Robles, E H
• Format: Article
• Language: English
• Subjects: Autoradiography; Cell Membrane - analysis; Cell Wall - analysis; Chromatography, Thin Layer; Culture Media; Drug Resistance, Microbial; Fatty Acids - analysis; Keto Acids - analysis; Lipids - analysis; Microscopy, Electron; Phosphatidylethanolamines - analysis; Phospholipids - analysis; Phosphorus - analysis; Phosphorus Radioisotopes; Pseudomonas - analysis; Pseudomonas - drug effects; Seawater; Sodium Chloride; Sucrose; Surface-Active Agents - pharmacology; Water Microbiology
• ISSN: 0021-9193

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.