Optimization for producing cell-bound lipase from Geotrichum sp. and synthesis of methyl oleate in microaqueous solvent

• Published in: Applied microbiology and biotechnology 2008-03, Vol.78 (3), p.431-439
• Main Authors: Yan, Jin-yong, Yan, Yun-jun
• Format: Article
• Language: English
• Subjects: Ammonium nitrate; Biological and medical sciences; Biosynthesis; Biotechnological Products and Process Engineering; Biotechnology; Carbon; Carbon sources; Cell-bound lipase; Cellular biology; Culture Media - chemistry; Enzyme Stability; Enzymes; Enzymes, Immobilized - metabolism; Factorial experiments; Fatty acids; Fundamental and applied biological sciences. Psychology; Geotrichum; Geotrichum - enzymology; Geotrichum - metabolism; Glucose; Industrial Microbiology; Life Sciences; Lipase - chemistry; Lipase - metabolism; Liquor; Methyl oleate; Microbial Genetics and Genomics; Microbiology; Nitrogen; Olea; Oleic Acids - biosynthesis; Olive oil; Optimization; Plackett-Burman design; Polyvinyl alcohol; Response surface analysis; Solvents; Solvents - metabolism; Studies
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-007-1331-z

An integrated optimization strategy involving a combination of different designs was employed to optimize producing conditions of cell-bound lipase (CBL) from Geotrichum sp. Firstly, it was obtained by a single factorial design that the most suitable carbon source was a mixture of olive oil and citric acid and the most suitable nitrogen source was a mixture of corn steep liquor and NH₄NO₃. Then, the Plackett-Burman design was used to evaluate the effects of 13 variables related to CBL production, and three statistically significant variables namely, temperature, olive oil concentration, and NH₄NO₃ concentration, were selected. Subsequently, the levels of the three variables for maximum CBL production were determined by response surface analysis as follows: 1.64% (v/v) olive oil, 1.49% (w/v) NH₄NO₃, and temperature 33.00°C. Such optimization resulted in a high yield of CBL at 23.15 U/ml, an enhanced 4.45-fold increase relative to the initial result (5.2 U/ml) in shake flasks. The dried CBL was used to synthesize methyl oleate in microaqueous hexane, resulting in 94% conversion after 24 h, and showed reusability with 70% residual activity and 69% conversion after eight cycles of batch operation, which indicating that CBL, as a novel and natural form of immobilized enzyme, can be effectively applied in repeated synthesis of methyl oleate in a microaqueous solvent.