BIOCHEMICAL-COMPOSITION OF MICROALGAE FROM THE GREEN ALGAL CLASSES CHLOROPHYCEAE AND PRASINOPHYCEAE .2. LIPID CLASSES AND FATTY-ACIDS

The fatty acid compositions of four species of green microalgae (Division Chlorophyta) from the class Chlorophyceac were compared with the compositions of six species of green microalgae from the class Prasinophyceae. Major fatty acids in the Chlorophyceae were 16:0, 16:1 (n- 13)t, 16:2(n-6), 16:3(n-3), 18:2 (n-6) and 18:3(n-3). In the species of Chlorophyceae examined, fatty acids with four or more double bonds were not detected, nor were any C2, and C22 fatty acids. Major fatty acids in the Prasinophyceae were 16:0, 16: 1 (n-13)t, 18:1(n-7), 16:4(n-3), 18:4(n-3), with variable proportions of 18:3(n-3), 18:5(n-3), 20:5(n-3) and 22:6(n-3). This is the first report of the unusual fatty acid 18:5(n-3) as a constituent of green microalgae. Most species from the Chlorophyceae do not produce the essential long-chain polyunsaturated fatty acids 20:5(n-3) and 22:6(n-3) required by most marine animals, and thus are generally not suitable as a single species algal food in hatcheries. However, species from the Prasinophyceae may supply sufficient quantities of these fatty acids in feeds for marine invertebrates.