FATTY ACID COMPOSITION DISTRIBUTION AND REQUIREMENTS OF 2 NONSTEROL-REQUIRING MYCOPLASMAS FROM COMPLEX BUT DEFATTED GROWTH MEDIA

The fatty acid composition, distribution, and requirements of two nonsterol-requiring mycoplasmas, Mycoplasma sp. KHS and Mycoplasma laidlawii B, grown in complex but exhaustively defatted growth media have been determined by high-resolving capillary gas chromatography. The residual fatty acid content of the two defatted growth media employed were 0.007 and 0.003%, respectively, with the unsaturated fatty acid content of each being less than 40% of the total (<0.0028 and 0.0014%, respectively). All cells were harvested during their late logarithmic phases of growth. Neither the qualitative nor quantitative fatty acid composition of these organisms or their anatomical components mimicked the trace residual fatty acid content of the growth medium that had survived solvent or solvent plus charcoal-lipid extraction. The need for preformed unsaturated fatty acids for growth of these organisms was judged to be minimal or nonexistent when grown under the conditions described. The monoenoic fatty acid synthetic capabilities of these organisms was also shown to be, at best, meager. Addition of various preformed long-chain monoenoic acids of the cis configuration to defatted growth media failed to either alter the growth rate, increase the cellular yields, or affect the microscopic morphology of the organisms examined. All cells and anatomical components showed an exceedingly high-saturated fatty acid content with the total unsaturated fatty acids present being almost negligible. The origin of these unsaturated fatty acids, in large part, was attributed to absorption from the medium. While palmitic acid is regarded as the predominating saturated fatty acid of microorganisms, myristic acid predominated in the lipids of these two mycoplasmas. Some evidence was obtained for the presence of exceedingly small quantities of branched methyl fatty acids in both organisms and anatomical components. The fatty acid composition of membranes and cytoplasm was found to mimic that of whole cells. Data were obtained illustrating a great variability in fragility between the membranes of Mycoplasma sp. KHS and M. laidlawii B, two sterolnonrequiring mycoplasmas, when obtained under comparable growth conditions and, otherwise, treated in identical fashion. The seemingly anomalous findings concerning an absolute requirement for an unsaturated fatty acid for growth of M. laidlawii documented by others and the findings presented herein are discussed. © 1969, American Chemical Society. All rights reserved.