The Effect of Long Chain Fatty Acid Isomers on Growth, Fatty Acid Composition and Osmotic Fragility of Mycoplasma laidlawii A

Abstract

SUMMARY: Growth of Mycoplasma laidlawii a in a tryptose medium, with lipid pre-extracted, containing charcoal-treated bovine plasma albumin, occurred only after addition of long-chain fatty acids. Of the long-chain fatty acids tested, positional as well as geometrical isomers of octadecenoic acids were effective in growth promotion; trans isomers were more effective in promoting growth and in lowering osmotic fragility than their corresponding cis isomers. Tetra-decenoic or hexadecenoic acids did not replace the growth requirement for an octadecenoic acid. Although fatty acids containing cyclopropane-rings promoted growth, a greater toxicity and lower growth response was observed. No fatty acid isomerization by this mycoplasma was detected and the octadecenoic acids added to the growth medium were recovered from membrane polar lipids unchanged. Fatty acid analyses revealed that myristic and palmitic acids were the major saturated fatty acid components of the membrane polar lipids. No differences were found in the fatty acid content or composition of membrane polar lipids from mycoplasmas grown at 25° and 37°. Major differences in the fatty acid composition between glycolipids and phospholipids were not apparent.