Dr. James Liao Wins 2010 Presidential Green Chemistry Challenge Academic Award; Second 2010 Green Chemistry Award for Advanced Biofuels
|Dr. James Liao has genetically engineered microorganisms to make higher alcohols from glucose or directly from carbon dioxide. Easel Biotechnologies. Click to enlarge.|
The US Environmental Protection Agency selected Dr. James Liao at UCLA as the recipient of the 2010 Presidential Green Chemistry Challenge Academic Award for his work in genetically engineering microorganisms to make higher alcohols (those with more than two carbons in the molecule) from glucose or directly from carbon dioxide. (Earlier post, earlier post.)
The award to Dr. Liao was the second for work on advanced biofuels within the five Green Chemistry awards made this year; the Small Business Green Chemistry award went to LS9, for its work on renewable biohydrocarbon fuels. (Earlier post.)
Higher alcohols, especially those with 3-8 carbon atoms, are useful as chemical feedstocks and transportation fuels. The efficient biosynthesis of these alcohols directly from carbon dioxide (CO2) or indirectly from carbohydrates would reduce net carbon emissions. However, native organisms do not synthesize these alcohols. Until now, none of these alcohols have been synthesized directly from CO2, and alcohols above five carbons have never been synthesized in the biosphere.
Dr. Liao, a professor at the University of California, Los Angeles (UCLA), co-founder and board member of Easel Biotechnologies and a founder of Gevo, has developed a microbial technology to produce alcohols with 3-8 carbon atoms from CO2. His technology leverages the highly active amino acid biosynthetic pathway, diverting its 2-keto acid intermediates toward alcohols.
With this technology, Professor Liao and his group have produced isobutanol from glucose in near-theoretical yields with high efficiency and specificity. They also transferred the pathway into a photosynthetic microorganism, Synechococcus elongatus PCC7942, which produces isobutyraldehyde and isobutanol directly from CO2. The engineered strain produces isobutanol at a higher rate than those reported for ethanol, hydrogen, or lipid production by cyanobacteria or algae. This productivity is also higher than the current rate of ethanol production from corn. The technology shows promise for direct bioconversion of solar energy and CO2 into chemical feedstocks, the EPA said in its award summary.
As fuel substitutes, higher alcohols have several advantages over ethanol, including higher energy density, lower hygroscopicity, and lower vapor pressure leading to better air quality. After excretion by the cells as aldehydes, the products are readily stripped from the bioreactor, avoiding toxicity to the microbes. Chemical catalysis then converts the harvested aldehydes to alcohols or other chemicals.
If 60 billion gallons of higher alcohols were used each year as chemical feedstocks and fuel (replacing 25% of gasoline), Dr. Liao’s technology could eliminate about 500 million tons of CO2 emissions or about 8.3% of the total US CO2 emissions, the EPA said. Easel Biotechnologies is commercializing the CO2-to-fuels technology under exclusive license from UCLA.
Easel is also a member of a consortium including UCLA and UC Davis that was awarded $4 million from ARPA-E to develop microorganisms using synthetic biology and metabolic engineering techniques to use electricity instead of sunlight for biological carbon dioxide fixation and fuel synthesis. This process will repurpose carbon dioxide for use as a liquid fuel that can be readily used as a high octane gasoline substitute. (Earlier post.)