The growing interest in applications of functional lipids such as polyunsaturated fatty acids, conjugated fatty acids and so on in various fields of health and dietary requirements has elicited much attention on the search and development of their new and rich sources.
Mycelia of a filamentous fungusMortierella alpina 1S-4 are potential source of triacylglycerols rich in arachidonic acid. Under the optimal culture conditions for large-scale production, the oil accumulated in the fungal mycelia reaches 500-600 mg/g dry mycelia (13.5-20 g/l). The oil contains 30-70% arachidonic acid in the total fatty acids. Mutant strains derived from M. alpina 1S-4 and defective in desaturases or elongases of arachidonic acid biosynthesis are useful for the production of oils containing unique polyunsaturated fatty acids of n-3, n-9 or other families.
Washed cells of several lactic acid bacteria well transform linoleic acid to the corresponding conjugated acids (CLAs) such as c9, t11- and t9, t11-CLAs. Hydration of linoleic acid to form the corresponding 10-hydorxyoctadecenoic acids and dehydration of the hydroxy acids to CLAs were suggested to be involved in this transformation.

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When the metabolism of carbon sources produces excess energy for cell activities, neutral lipids such as triacylglycerol and sterol ester are stored in fungi and yeasts. These storage lipids are mainly localized in lipid bodies, which are separated from other intracellular membranes. This paper reviews recent findings on the biosynthesis and assembly of storage lipids, especially triacylglycerol, in fungi and yeasts. Particular emphasis is placed on recent progress in gene cloning of triacylglycerol biosynthetic enzymes, which makes it possible to study molecular mechanisms underlying the biosynthesis and assembly of storage lipids in lipid bodies. Our recent works on triacylglycerol biosynthesis and lipid body formation in the oleaginous fungus, Mortierella ramanniana var. angulispora are also described.

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