UCLA Scientists Create Bacteria to Consume CO2 and Produce Liquid Isobutanol Fuel Via Photosynthesis

Global climate change has prompted efforts to drastically reduce emissions of carbon dioxide, a greenhouse gas produced by burning fossil fuels. Synthetic biology may hold the answer.  In a new approach, researchers from the UCLA Henry Samueli School of Engineering and Applied Science have genetically modified a cyanobacterium to consume carbon dioxide and produce the liquid fuel isobutanol, which holds great potential as a gasoline alternative. The reaction is powered directly by energy from sunlight, through photosynthesis.

 

Genetically engineered strains of the cyanobacterium Synechococcus elongatus in a Petri dish

Image Credit:: UCLA

The research appears in the Dec. 9 print edition of the journal Nature Biotechnology and is available online.

 

This new method has two advantages for the long-term, global-scale goal of achieving a cleaner and greener energy economy, the researchers say. First, it recycles carbon dioxide, reducing greenhouse gas emissions resulting from the burning of fossil fuels. Second, it uses solar energy to convert the carbon dioxide into a liquid fuel that can be used in the existing energy infrastructure, including in most automobiles.

 

While other alternatives to gasoline include deriving biofuels from plants or from algae, both of these processes require several intermediate steps before refinement into usable fuels.

 

"This new approach avoids the need for biomass deconstruction, either in the case of cellulosic biomass or algal biomass, which is a major economic barrier for biofuel production," said team leader James C. Liao, Chancellor's Professor of Chemical and Biomolecular Engineering at UCLA and associate director of the UCLA–Department of Energy Institute for Genomics and Proteomics. "Therefore, this is potentially much more efficient and less expensive than the current approach."

 

Using the cyanobacterium Synechoccus elongatus, researchers first genetically increased the quantity of the carbon dioxide–fixing enzyme RuBisCO. Then they spliced genes from other microorganisms to engineer a strain that intakes carbon dioxide and sunlight and produces isobutyraldehyde gas. The low boiling point and high vapor pressure of the gas allows it to easily be stripped from the system.

 

The engineered bacteria can produce isobutanol directly, but researchers say it is currently easier to use an existing and relatively inexpensive chemical catalysis process to convert isobutyraldehyde gas to isobutanol, as well as other useful petroleum-based products.

 

In addition to Liao, the research team included lead author Shota Atsumi, a former UCLA postdoctoral scholar now on the UC Davis faculty, and UCLA postdoctoral scholar Wendy Higashide.

 

An ideal place for this system would be next to existing power plants that emit carbon dioxide, the researchers say, potentially allowing the greenhouse gas to be captured and directly recycled into liquid fuel.

 

"We are continuing to improve the rate and yield of the production," Liao said. "Other obstacles include the efficiency of light distribution and reduction of bioreactor cost. We are working on solutions to these problems."

 

The research was supported in part by a grant from the U.S. Department of Energy.

 

The UCLA Henry Samueli School of Engineering and Applied Science, established in 1945, offers 28 academic and professional degree programs, including an interdepartmental graduate degree program in biomedical engineering. Ranked among the top 10 engineering schools at public universities nationwide, the school is home to seven multimillion-dollar interdisciplinary research centers in wireless sensor systems, nanotechnology, nanomanufacturing and nanoelectronics, all funded by federal and private agencies.

CO2 Solution Reveals Enzymatic Process for Recycling Power Plant CO2 Emissions

CO2 Solution Inc. (Quebec, Canada) received United States patent, 7,596,952 for a process and a plant for recycling carbon dioxide emissions from power plants into useful carbonated species. The patent provides for exclusivity in the field of using the enzyme carbonic anhydrase, or an analog thereof, for the capture of CO2 from any fossil power plant, where captured CO2 is converted into a carbonated species. The company believes that the patent has potentially significant value for efficient carbon capture in coal and other fossil fuel power plants.

The process for recycling carbon dioxide emissions from a fossil-fuel power plant into useful carbonated species primarily consists  of the steps: a) combustion of a fossil fuel, thereby generating heat and a hot exhaust gas containing CO2 and b) converting the heat into energy. The process is characterized in that it further comprises the steps of: c) cooling the exhaust gas; and d) biologically transforming at least a portion of the CO2 contained in the cooled exhaust gas into carbonated species, thereby obtaining a low CO2 exhaust gas and producing useful carbonated species. The low CO2 exhaust gas obtained in step d) can be released in the atmosphere without increasing the problem of greenhouse effect.

This patent is the fourth new patent received by CO2 Solution during 2009, in addition to the following:

U.S. Patent 7,514,056 ‐ Process and installation for the fractionation of air into specific gases; Protects the use of carbonic anhydrase for use in efficiently capturing CO2 from compressed air as part of an air‐separation unit for the production of oxygen. The Company believes that the patent can address the cost challenge that conventional air‐separation processes face due to ever increasing CO2 concentrations in ambient air. The specialty gas industry has shown interest in the patent and CO2 Solution intends to pursue possible commercialization opportunities therein.

U.S. Patent 7,521,217 ‐ Carbonic anhydrase having increased stability under high temperature conditions; Covers the Company’s proprietary enzyme ‘mutants’ which have increased thermal and industrial stability through genetic engineering.

Canadian Patent 2,443,222 ‐ A process and plant for the production of Portland cement clinker (equivalent U.S. Patent 6,908,507); Covers the use of the enzyme for the capture of CO2 from cement plant flue gas and the production of calcium carbonate for reuse in the cement making process, and has the potential to materially reduce overall carbon emissions from the cement production process.

Regarding the issuance of these four new patents, Mr. Glenn Kelly, President & CEO stated: “These patents build on our already broad intellectual property portfolio in enzymatic carbon capture, at a time when industry is increasingly searching for new ways to capture CO2 that are more efficient than conventional scrubbing technology. There has recently been heightened interest in the use of carbonic anhydrase in this context. As such, we believe these patents further solidify CO2 Solution’s technology leadership position in the field, and in the rapidly growing carbon capture space.”