Genetic improvement of EPA content in microalgae
Polyunsaturated fatty acids (PUFAs) have been receiving increasing attention due to their involvement in human health. Several of them, specifically linoleic acid (LA, 18:2(n-6)), cl-linolenic acid (ALA, 18:3(n-3)), y-linolenic acid (GLA, 18:3(n-6)) and arachidonic acid (AA, 20:4(n-6)) are considered essential for human nutrition (WHO/FAO, 1977). On the other hand, eicosapentaenoic acid (EPA, 20:5(n-3)) has recently been found to be beneficial in coronary disease (Nelson, 1972; van Gent et al., 1979; Bronsgeest-Schoute et al., 1981; Dyerberg, 1986; Singh and Chandra, 1988; Simopoulos, 1991; Iacono and Dougherty, 1993; Nettleton, 1993), and its positive effect in certain types of cancer, and other aspects of human health has also been suggested (Cohen el al., 1995). Finally, docosahexaenoic acid (DHA, 22:6(n-3)) is involved mainly in the development of the nervous system and retina (Innis, 199 1; Brown, 1994).