For humans, diet is the only source of the essential fatty acids. They are precursors of long chain polyunsaturated fatty acids, eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). DHA and EPA consumption is associated with numerous human health benefits including reduced coronary vascular disease, blood pressure, inflammatory and autoimmune disorders. Fish oil and algae are the two major sources of DHA and EPA. Dietary supplementation of fish oil and algae has some serious problems due to fish oil off-flavor and prompt oxidation of polyunsaturated fatty acids. Feeding dairy cows with fish oil and algae to increase the DHA and EPA in milk had limited success because rumen hydrogenation changes the fatty acid profile from what was fed. Also, feeding dairy cows with polyunsaturated fatty acids caused significant decreases in feed intake, milk and milk fat production.

The rapidly growing biodiesel industry generates crude glycerol as a by-product from the transesterification of the oils. These quantities of glycerol have glutted the glycerol market. There is an immediate need for innovative methods for crude glycerol utilization into value-added product to increase biodiesel production efficiency and costs.

The oleaginous yeast Cryptococcus curvatus, previously known as Apiotrichum curvatum ATCC 20509 and Candida curvata, was discovered at Iowa State University in 1978. This yeast was reported as an efficient oil producer and easy to grow with minimal nutritional requirements. An important C. curvatus characteristic is ability to utilize a wide range of substrates including glycerol and oils and convert them into lipids that are stored as intracellular triacylglycerols. This ability to encapsulate fed fatty acids may have significant uses as a means to protect long chain polyunsaturated fatty acids, which are prone to oxidation. Thus, microbial encapsulation of polyunsaturated fatty acids into Cryptococcus curvatus may be a solution for the off-flavor, oxidation, and biohydrogenation problems. Moreover, there is a potential that crude glycerol could be converted into oil by Cryptococcus curvatus and further transesterified into biodiesel.