ARS | Publication request: Production of biodiesel by transesterification of corn and soybean oils with ethanol or butanol using resin-bound truncated Candida antarctica lipase B

Submitted to: Journal of Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 24, 2012
Publication Date: February 11, 2012
Citation: Hughes, S.R., Moser, B.R., Robinson, S., Cox, E.J., Harmsen, A.J., Friesen, J.A., Bischoff, K.M., Jones, M.A., Pinkleman, R., Bang, S.S., Tasaki, K., Doll, K.M., Qureshi, N., Liu, S., Saha, B.C., Jackson, Jr., J.S., Cotta, M.A., Rich, J.O., Caimi, P. 2012. Synthetic resin-bound truncated Candida antarctica lipase B for production of fatty acid alkyl esters by transesterification of corn and soybean oils with ethanol or butanol. Journal of Biotechnology. 159:69-77. DOI: 10.1016/j.jbiotec.2012.01.025.

Interpretive Summary: The ability to produce biodiesel from the by-products of ethanol and other alcohol production processes would create a less expensive source of biodiesel. It would also add value to the ethanol production process. Large quantities of certain enzymes are essential to accomplish this, which requires optimization of lipase enzymes and the development of specific microbial strains. This research produced a gene for a shortened synthetic lipase enzyme to determine the minimum length needed to maintain enzyme activity. The enzyme was produced at high levels in a yeast strain similar to that used in fuel ethanol production, attached to a resin, and used in the manufacture of biodiesel from corn oil, soybean oil, ethanol and butanol. The resin-bound enzyme produced more biodiesel and is potentially less expensive to produce than a commercially available lipase resin under the same conditions. This research would enable the cost-effective and environmentally benign production of additional value-added products, such as biodiesel, from by-products (mainly low-grade corn oil) and products (ethanol) of the existing fuel ethanol process.

Technical Abstract: Enzymatic catalysts, such as lipases, have advantages over chemical catalysts for transesterification of triglycerides to produce biodiesel. A gene encoding a synthetic truncated Candida antarctica lipase B (CALB) was generated via automated PCR and expressed in Saccharomyces cerevisiae. Western blot analysis detected five truncated CALB variants, suggesting multiple translation starts from the six in-frame ATG codons. The longest open reading frame, which corresponds to amino acids 35 to 317 of the mature lipase, appeared to be expressed in the greatest amount. The truncated CALB was immobilized on Sepabeads® EC-EP resin and used to produce ethyl and butyl esters from crude corn oil and refined soybean oil. The yield of ethyl esters was 4-fold greater from corn oil than from soybean oil and was 36% and 50% higher, respectively, when compared to a commercially available lipase resin (Novozym 435) using the same substrates. A 5:1 (v/v) ratio of ethanol to corn oil produced 3.7-fold and 8.4-fold greater yields than ratios of 15:1 and 30:1, respectively. With corn oil, butyl ester production was 56% higher than ethyl ester production. Addition of an ionic catalytic resin step prior to the CALB resin increased yields of ethyl esters from corn oil by 53% compared to CALB resin followed by ionic resin.