Docosahexaenoic acid (DHA) from marine single cell organisms (Thraustochytrids)

Marine fish oils may becom a limitin factor for farming of salmon and marine fishes; e.g., halibut. Plant oil used in fish feed may have to be fortified with docosahexaeonic acid (DHA), which is the dietary most important fatty acid of marine origin. Traustochytrids are eukaryotic single cell organisms, which are widespread in marine coastal waters.They grow heterotrophically on simple carbon and nitrogen sources and accumulate triglycerides for reserve energy. Their lipid content may account for nearly 80% of the cell dry weight, and DHA may account for more than 60% of their total fatty acids. Internationally, fermentation processes based on thraustochytrids are now being developed for production of DHA for human consumption. We will try to utilize this marine resource for production of DHA for fish feed. T o achieve a production cost that can be tolerated by the fish farming industry, we will have to increase the productivity above the previously published results. To achieve thes goal, we will screen for new strains, which have a high content of DHA and grow well in fermentors. These strains will be used for optimizing the fermentation process and studies on physiology, metabolism and rout of DHA synthesis.