Quantitative measurement of the effectiveness of unsaturated fatty acids required for the growth of Saccharomyces cerevisiae.

The growth response of a mutant of Saccharomyces cerevisiae which is unable to synthesize unsaturated fatty acids has been measured in the presence of variable concentrations of exogenous unsaturated fatty acids. Final cell yields, doubling times, and lag times were all found to vary as a function of the initial concentration of the added unsaturated acid. The cell yield was found to be a convenient quantitative measurement to use in comparing the effectiveness of various unsaturated acids. Values for the acids ranged from 1.7 to 11 cells per femtomole with values for oleate and palmitoleate at 2.7 and 4.3 cells per femtomole, respectively. In general, the effectiveness of unsaturated acids was found to increase with an increasing number of double bonds. Saturated fatty acids of a chain length of 5 to 18 carbon atoms were completely ineffective. The varied efficiencies of different unsaturated fatty acids indicate that unsaturation per se was not the basis of the nutritional requirement and indicate certain acids that would be useful in further studies of the role of unsaturated acids in cell function.