Lipids and fatty acids of a moderately halophilic bacterium, no. 101

Abstract

The extractable and bound lipids of a moderately halophilic gram-negative rod, strain No. 101 (wild type) grown in a medium containing 2 M NaCl, were examined. The extractable lipids were separated into at least 8 components by using thin-layer chromatography. The major phospholipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an unidentified phosphoglycolipid in the whole cells, cell envelopes and outer membrane preparations, commonly. Judging from mild alkaline hydrolysis and enzymatic treatment with phospholipase A 2, C and D, the unidentified phosphoglycolipid possessing P i glycerol, fatty acids and glucose in a molar ratio of 1 : 2 : 2 : 1, appeared likely to be a glucosyl derivative of phosphatidylglycerol. No glucuronic acid containing lipid was detected. The extractable lipid composition varied greatly with the concentrations of NaCl in the medium and the stages of bacterial growth. The most characteristic phosphoglycolipid in this organism increased up to 25% of the total phospholipids with the addition of 1% glucose in the medium. The major fatty acids of the extractable lipids were C 16:0, C 16:1, C 18:0, C 18:1 and cyclopropanoic C 17 and C 19 acids and these compositions were very similar for each phospholipid. The cyclopropanoic fatty acids predominated as growth proceeded. The fatty acids of the bound lipids comprised a high concentration of 3-hydroxydodecanoic acid. The esterified fatty acids of the lipopolysaccharide molecule seemed to contain a wide variety of hydroxy and non-hydroxy shorter chain fatty acids, while the amide-linked fatty acids consisted almost entirely of 3-hydroxydodecanoic acid.