Iso-Fatty Acids and Methyl Esters

In bacteria, the iso-fatty acid1 content and composition can often be used as a taxonomic marker because iso-fatty acids are often found in bacteria but not commonly in other microorganisms.2 They are found in small amounts in marine organisms and ruminants, mainly due to the food chain but also due to some de novo synthesis. Some waxy materials such as lanolin, as well as secretions near animal eyes, contain an unusually high amount of iso-fatty acids being employed for their lubricating effect. Branched chain fatty acids are critical for the regulation of fluidity in membranes and in membrane transport for many types of bacteria due to their significantly lower transition temperature than straight chain fatty acids. Some bacteria handle stress (such as heat and toxicity) by changing the ratio of anteiso/iso-fatty acids in the cell membrane. Iso-fatty acids have been found to be activators for various enzymes and are used as protein modifiers. Although iso-even chain fatty acids are commonly derived from isobutyryl-CoA, some bacteria derive all iso-even chain fatty acids via alpha-oxidation of iso-odd chain fatty acids.3


  1. T. Kaneda “Iso- and Anteiso-Fatty Acids in Bacteria: Biosynthesis, Function, and Taxonomic Significancet” American Society for Microbiology, Vol. 55(2) pp. 288-302, 1991
  2. N. Jensen and M. Gross “Fast Atom Bombardment and Tandem Mass Spectrometry for Determining Iso- and Anteiso-Fatty Acids” Lipids, Vol. 21(5) pp. 362-365, 1986
  3. H. Bode et al. “Biosynthesis of Iso-Fatty Acids in Myxobacteria: Iso-Even Fatty Acids Are Derived by alpha-Oxidation from Iso-Odd Fatty Acids” J. Am. Chem. Soc., Vol. 127(2) pp 532–533, 2005

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