Submitted to: Biotechnology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 24, 2004
Publication Date: June 1, 2004
Citation: Hsu, A.C., Jones, K.C., Foglia, T.A., Marmer, W.N. 2004. Transesterification activity of lipases immobilized in phyllosilicate sol-gel matrix. Biotechnology Letters. 26:917-971. Interpretive Summary: Biodiesel (simple mono-alkyl esters of vegetable oils and fats) is beginning to be used as diesel engine fuel. To reduce the cost of biodiesel, inexpensive feedstocks should be used for its production. An enzyme approach can effectively produce biodiesel from such feedstocks, but available enzymes are not effective in producing biodiesel. We developed a novel method to immobilize enzymes by entrapping them within a sol-gel matrix. This allowed a continuous enzymatic process for biodiesel production. In this report, we investigate several immobilized lipases for their ability to synthesize biodiesel. Using various fats and oils (tallow, grease, corn, soybean, palm and menhaden) we have investigated the ability of many different immobilized enzymes to produce biodiesel. The results show that immobilized enzymes are potential biocatalysts for biodiesel production from a variety of feedstocks, including those such as spent restaurant grease that had suffered degradation in their initial use.
Technical Abstract: Lipases Pseudomonas cepacia (PS-30) and Thermomyces lanuginosa ( T.l.) were immobilized in a phyllosilicate sol-gel matrix and then studied for their transesterification activity. Both immobilized lipases were able to catalyze ester formation from various fats or oils containing a wide range of free fatty acids (2.6 to 36%). Immobilized (IM) T.l. lipase had much higher transesterification activity toward fats and oils with low amounts of free fatty acids or saturated triacylglycerides. At an equal amount of protein used, IM-T.l. lipase showed a fast rate of alkyl ester production. For long incubations, IM PS-30 could reach slightly higher levels of alkyl ester production. Molecular sieves had no effect on IM T.l. transesterification activity. Time course studies of IM PS-30 and IM T.l. on the ethanolysis of various greases and fats indicated that IM T.l. lipase transesterifies a broad spectrum of greases and oils regardless of the chain length or the degree of unsaturation in the triglyceride acyl moiety, while IM PS-30 favors triglycerides containing acyl moieties of medium or long chains. T.l. and PS-30 lipases immobilized in a phyllosilicate sol-gel matrix are potential catalysts for production of biodiesel.