Abstract
The most remarkable difference between a chemical reaction and a lipase reaction is the fact that lipase possesses several substrate specificities, in particular, fatty acid specificity on hydrolysis, esterification, or transesterification reaction of the ester bond. Several lipases act weakly on polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA) and arachidonic acid. Through fatty acid specificity of lipases, a DHA-rich oil (acylglycerols) has been industrially produced from tuna oil. Lipase specificity also facilitates purification of PUFAs, conjugated linoleic acid isomers, tocopherols, and sterol esters and production of triacylglycerol that is DHA– rich at the sn– 1(3) position. Microorganism-mediated processes using Aeromonas hydrophila N– 6 are effective for production of rare unsaturated fatty acids and rare unsaturated fatty alcohols from several vegetable oils. These lipids are rarely observed in natural oils. We also demonstrate that Acinetobacter sp. N– 476– 2 effectively converts functional arachidonic acid to functional arachidonyl alcohol, which can be used as a substrate for medicine.
Keywords: Arachidonic acid, conjugated linoleic acid, docosahexaenoic acid, functional lipid, lipase, microbial conversion, plant sterol, polyunsaturated fatty acid.