Effect of Growth Temperature on the Lipid Composition of Cyanidium caldarium

Cyanidium caldarium was grown at 20 and 55 C and harvested during exponential growth phase. Lipids were extracted and separated by silicic acid column and thin layer chromatography. The major glycolipids were identified as mono- and digalactosyl diglyceride and sulfolipid. Major phospholipids were identified as phosphatidyl choline and phosphatidyl ethanolamine. The cells grown at 20 C contained significantly larger quantities of these glycolipids and phospholipids than cells grown at 55 C.Fatty acid analysis showed that in all cases the cells grown at 20 C contained more unsaturated fatty acids than the cells grown at 55 C. Cells grown at 55 C were shown to lack linolenic acid, in contrast to cells grown at 20 C, which contained appreciable quantities in certain lipid components. For example, monogalactosyl diglyceride had 57% of its fatty acids in the form of linolenic acid. Cells grown at 55 C were 10 to 15 C more stable to disruption by heating than cells grown at 20 C. The greater thermostability of the latter was attributed to a higher degree of saturation of their membrane fatty acids.