Fatty acid profile of Isochrysis galbana clone T.ISO at log and stationary phases

Marine microalgae, or phytoplankton, provide the food base which supports the entire animal population of the open sea. Most algal classes are represented in ocean populations: the best known are the diatoms (Bacillariophyta), the dinoflagellates (Dinophyta), the green algae (Chlorophyta) and the blue-green algae (Cyanophyta).

Three species of marine microalgae – Skeletonema costatum, a diatom, and two flagellates, Isochrysis galbana, and Tetra-selmis suecica are widely used as food for growing larvae in shellfish hatcheries along the Irish coast. The combination of the three organisms ensures a balanced supply of the v3 and v6 fatty acids for healthy growth and survival of the larvae, and several studies have shown that the critical factor in this diet is the content of EPA and DHA. Our current work in the Department of Life Sciences (GMIT) is concerned with the qualitative and quantitative analysis of the fatty acids of these microalgae, as no detailed study of the fatty acid composition of the indigenous organisms has been carried out to date.

The microalgae are the primary source of EPA and DHA. Humans obtain their supplies indirectly by the consumption of oily fish in their diets, and there are also numerous products, including the traditional cod liver oil, available in healthfood stores. But the intake of fish or fish products is regarded as being grossly inadequate in the current Irish diet: the low incidence of heart disease among Greenland Eskimos, Japanese and Icelanders is attributed to the high proportion of marine fish in their diet. There is growing evidence that EPA and DHA play an extremely important role in the prevention and treatment of atherosclerosis, thrombosis and high blood pressure, of inflammatory conditions such as asthma, arthritis, migraine headache and psoriasis, and of cancer such as breast, colon and prostate cancers.

The next phase in our studies will involve screening and selection of microalgae for their EPA and DHA content, and the manipulation of their growth conditions to maximise the production of these important w3 fatty acids. Declining fish stocks and the anticipated increase in human demand dictate that an alternative source of EPA and DHA will have to be found. The microalgae would seem to be the ideal source to fill this gap.

Contact: ide.nifhaolain@gmit.ie