MICROALGAE AS A SOURCE OF FATTY-ACIDS

Microalgae are a very diverse group of organisms that consist of both prokaryotic and eukaryotic forms. Although most microalgae are phototr ophic, some species are also capable of heterotrophic growth. Some spe cies of microalgae can be induced to overproduce particular fatty acid s through simple manipulations of the physical and chemical properties of the culture medium. As a result of the profound differences in cel lular organization and growth modes and the ability to manipulate thei r fatty acid content, microalgae represent a significant source of unu sual and valuable lipids and fatty acids. The utilization of microalga l lipids and fatty acids as food components requires that these organi sms be grown at large scale under controlled conditions. Several growt h systems have been developed for large scale growth of phototrophic m icroalgae using either natural sunlight or artificial light, but their lack of control of culturing parameters or their high cost of operati on have limited their utility for the production of food products. Ins tead, large scale cultivation of heterotrophic microalgae using classi cal fermentation systems provides consistent biomass produced under hi ghly controlled conditions at low cost. Microalgae contain many of the major lipid classes and fatty acids found in other organisms. However , they are also the principal producers in the biosphere of some polyu nsaturated fatty acids, especially docosahexaenoic acid (DHA). The hig h DHA content found in some algae is currently being utilized to suppl ement infant formula to enable it to more closely resemble human breas t milk. Thus, the commercialization of DHA from microalgae demonstrate s the value of these organisms as a source of useful fatty acids.