Biological Synthesis of Fuels and Chemicals
Dr. James C. Liao, Chancellor’s Professor, Chemical and Biomolecular Engineering, UCLA
Thursday July 22, 2010 2-3PM EDT
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Global energy and climate problems have stimulated increased efforts in synthesizing fuels and chemicals from renewable resources. Compared to the traditional biofuel, ethanol, higher alcohols offer advantages as gasoline substitutes because of their higher energy density and lower hygroscopicity. However, these alcohols cannot be synthesized economically using native organisms. Here we present a metabolic engineering approach using various microorganisms to produce higher alcohols (C3-C8) from renewable carbon source. This strategy leverages the host’s highly active amino acid biosynthetic pathway and diverts its 2-keto acid intermediates for alcohol synthesis. In particular, we have achieved high yield, high specificity production of isobutanol from glucose. We further developed a non-natural chain-elongation pathway to produce abiotic longer chain keto acids and alcohols by engineering the chain elongation activity of 2-isopropylmalate synthase and altering the substrate specificity of downstream enzymes through rational protein design. When introduced into E. coli, this non-natural biosynthetic pathway produces various long-chain alcohols with carbon number ranging from 5 to 8. This strategy has also been implemented in photosynthetic cyanobacteria, Synechococcus elongates to produce isobutyraldehyde and isobutanol directly from CO2, bypassing the need for plant or algal biomass processing. In addition, other non-natural metabolites which can be used as pharmaceutical intermediates can be produced using this strategy.
Dr. James C. Liao, Chancellor’s professor, Chemical and Biomolecular Engineering, UCLA, is a pioneer in Metabolic Engineering, Synthetic Biology, and Systems Biology. He received his BS degree from National Taiwan University and PhD from University of Wisconsin-Madison. After working as a research scientist at Eastman Kodak Company, Rochester, NY, he started his academic career at Texas A&M University in 1990 and moved to UCLA in 1997. He was elected Fellow of American Institute for Medical and Biological Engineering, 2002, and received numerous awards, including NSF Young Investigator Award (1992), Merck Award for Metabolic Engineering (2006), Food, Pharmaceutical, and Bioengineering Division award of American Institute of Chemical Engineers (AIChE) (2006), Charles Thom Award of the Society for Industrial Microbiology (2007), Marvin Johnson Award of American Chemical Society (2009), Alpha Chi Sigma Award of AIChE (2009), James E. Bailey Award of Society for Biological Engineering (2009), and the 2010 Presidential Green Chemistry Challenge Award.