LIPID COMPOSITION OF MESOPHILIC AND PSYCHROPHILIC YEASTS (CANDIDA SPECIES) AS INFLUENCED BY ENVIRONMENTAL TEMPERATURE

The lipids of three psychrophilic yeasts of the genus Candida, grown at 10°, were compared with those of a mesophilic yeast (Candida lipolytica) grown at 25° and at 10°. All the yeasts examined had similar contents of total lipids and of phosphatides, and similar phosphatide and neutral lipid compositions. However, the total fatty acids of the psychrophiles and of the mesophile grown at 10° had much higher proportions of linoleic acid and lower proportions of oleic acid than those of the mesophilic yeast grown at 25°; the psychrophilic yeasts also contained linolenic acid, not detected in the mesophilic yeast. The fatty acid composition of the psychrophilic yeast remained fairly constant during its growth cycle, but that of the mesophilic yeast at 10° showed marked changes in the proportions of oleic and linoleic acids in the early stages of growth; similar changes occurred in the mesophile grown at 25°, but at much faster rates. On the basis of these observations and others it is concluded that in the early stages of growth of the mesophile at 25° and 10°, oleic acid is converted rapidly to linoleic, which is then oxidatively metabolized during the later stages of active growth. The higher proportions of linoleic acid in the mesophile grown at 10° could be accounted for by a slower rate of metabolism of linoleic acid during the later stages of growth at the lower temperature.