Lipid and Fatty-acid Composition of Diatoms

The lipids and fatty acids of two freshwater diatoms Nitzschia palea Kutz, Navicula muralis Lewin, and one marine species, Navicula incerta Grun. have been studied. The major lipid components in all species were triglycerides, monogalactosyl, digalactosyl and sulphoquinovosyl diglycerides, phosphatidyl glycerol, phosphatidyl choline (lecithin), and phosphatidyl ethanolamine; while palmitoleic, palmitic, eicosapentaenoic and eicosate-traenoic acids were the major fatty acid constituents. The two galactolipids, monogalactosyl and digalactosyl diglycerides contained large amounts of C16 and C20 polyunsaturated fatty acids. Lipids of diatoms, whether grown in the light or in the dark, were the same apart from quantitative differences. More storage lipids such as triglycerides were synthesized in the light than in the dark.