Polar lipids and fatty acids of Pseudomonas cepacia

The polar lipids and fatty acids produced by the reference strains for seven different O serogroups of Pseudomonas cepacia have been identified. Similar results were obtained for all strains. Contrary to a previous report, the only significant phospholipids in this species are phosphatidylethanolamine and bis(phosphatidyl)glycerol, which contributed 57-83% and 17-43%, respectively, of the total lipid phosphorus. The former lipid was found as two chromatographically distinct fractions. In the less polar fraction and in bis(phosphatidyl)glycerol, the major fatty acids were hexadecanoic acid, cis-9,10-methylenehexadecanoic acid, cis-octadec-11-enoic acid, and cis-11,12-methyleneoctadecanoic acid. In the more polar fraction of phosphatidylethanolamine, the fatty acid in one position is a 2-hydroxy acid, mainly 2-hydroxyhexadecenoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecenoic acid, or 2-hydroxymethyleneoctadecanoic acid. Compared with other phospholipids, this fraction of phosphatidylethanolamine was depleted in cis-9,10-methylenehexadecanoic acid. Each strain also produced two ornithine amide lipids. In the major lipid, 3-hydroxyhexadecanoic acid was amide-bound to the alpha-amino group and was itself probably esterified by a 2-hydroxy acid, mainly 2-hydroxyoctadecenoic acid or the derived cyclopropane acid. In the minor ornithine amide lipid, the ester-bound acids were mainly methyleneoctadecanoic acid and hexadecanoic acid. The unusual lipid profiles of P. cepacia are of chemotaxonomic interest.