The monoenoic fatty acid composition of a marine species ofDesulfobulbus grown on lactate

Abstract

The proportions of isomeric monoenoic fatty acids from cell lipids of a marine, anaerobic, sulphatereducing bacteriumDesulfobulbus, grown on lactate, were determined by pyrrolidide derivatization and GC-MS analysis. The predominant fatty acid was C17ŋ1, Δ11 with much smaller proportions of C16∶1, Δ11 and C18∶1, Δ11 and small (<5%) yet significant proportions of C15∶1, Δ11; C16∶1, Δ9; C17∶1, Δ9 and C18∶1, Δ9. If the spectrum of isomers obtained from this organism were synthesized entirely by the anaerobic pathway, it would indicate a wider chain-length specificity for the ratelimiting β-hydroxy acyl dehydrase than hitherto has been reported. The high proportion of oddnumbered fatty acids reflected the chain initiation by propionate derived from lactate. The possibility of monoene synthesis by an anaerobic Δ9-desaturase mechanism is discussed.