Effect of Growth Temperature on the Lipid Composition of Cyanidium caldarium: I. Class Separation of Lipids.

Cyanidium caldarium was cultured at 20 and 55 C and harvested during exponential growth phase. Comparative lipid studies on each cell type show a decrease by one-half of the total lipid in cells grown at 55 C over cells grown at 20 C. While the distribution of lipid into each of five lipid classes was not influenced by high temperature (55 C), the degree of unsaturation was greatly affected. Ratios of unsaturated to saturated fatty acids in these cells decreased 3-fold with increased temperature in the growth environment. Cells cultured at 20 C contained 30% of their fatty acids as linolenic while this fatty acid could not be detected in cells cultured at 55 C.

Effect of Growth Temperature on the Lipid Composition of Cyanidium caldarium: II. Glycolipid and Phospholipid Components.

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.