|Kim, Beom soo|
Submitted to: Book Chapter
Publication Type: Book / chapter
Publication Acceptance Date: 5/21/2007
Publication Date: 8/30/2008
Citation: Kim, B., Song, B., Hou, C.T. 2008. Production of lipase and oxygenated fatty acids from vegetable oils. In: Hou, C.T., editor. Biocatalysis and Bioenergy. New York, NY:John Wiley & Sons. p. 547-555. Interpretive Summary:
Technical Abstract: Vegetable oils such as soybean oil and corn oil are cheap raw materials. Various value-added oxygenated fatty acids have been produced from unsaturated fatty acids such as oleic and linoleic acid by biotransformation. Lipase from the non-pathogenic yeast Candida cylindracea is another important value-added industrial product with wide applications that can be produced from surplus vegetable oils. High cell density is often necessary for high yield and productivity. One of the most popular methods to achieve high cell density is fed-batch culture by controlling the nutrient feeding. We carried out high cell density fed-batch cultures of C. cylindracea to increase cell concentration and extracellular lipase activity. Two feeding strategies, intermittent and stepwise feeding, were compared for cell growth and lipase production. The highest extracellular lipase activity was 23.7 U/ml when micro-set was 0.02 h-1, while the highest lipase productivity was 0.31 U/ml/h at micro-set of 0.08 h-1. Highest lipase activity was obtained by preventing the build-up of oleic acid in culture broth during the later part of fed-batch culture. Hydroxy fatty acids have gained important attention because of their special properties such as higher viscosity and reactivity compared with other non-hydroxy fatty acids. We reported earlier that a microbial isolate, Flavobacterium sp. strain DS5, produced 10-ketostearic acid (10-KSA) from oleic acid in 85% yield. The product purified was white, plate-like crystals melting at 79.2 deg C. To develop an industrial process for the production of these new oxygenated fatty acids, the productivity needs to be increased. Fed-batch cultures were carried out to improve 10-KSA production. The same stepwise feeding strategy as used for lipase production by C. cylindracea was employed to grow cells to high density and produce 10-KSA. Stepwise feeding was started at 7 h. When the optical density increased to 54.4 in 35 h, nutrient feeding was stopped and oleic acid was added. 10-HSA concentration reached 8 g/L at 47 h and then decreased. 10-KSA concentration started to increase with decreasing 10-HSA concentration, showing that 10-HSA converted to 10-KSA. The final 10-KSA concentration was 12 g/L in 83 h, which was 4 to 5 times that in flask culture (2.5 to 3.5 g/L).