UCLA researchers engineer bacteria to turn carbon dioxide into liquid fuel

December 10, 2009

Global climate change has prompted efforts to drastically reduce emissions of carbon dioxide, a greenhouse gas produced by burning fossil fuels.

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.

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."
-end-
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.

For more news, visit the UCLA Newsroom or follow us on Twitter.

University of California - Los Angeles

Related Greenhouse Gas Articles from Brightsurf:

Make your own greenhouse gas logger
Researchers at Linköping University's Department of Thematic Studies, Environmental Change, have developed a simple logger for greenhouse gas flows.

Old carbon reservoirs unlikely to cause massive greenhouse gas release
As global temperatures rise, permafrost and methane hydrates -- large reservoirs of ancient carbon -- have the potential to break down, releasing enormous quantities of the potent greenhouse gas methane.

Mediterranean rainfall immediately affected by greenhouse gas changes
Mediterranean-type climates face immediate drops in rainfall when greenhouse gases rise, but this could be interrupted quickly if emissions are cut.

Seeking better guidelines for inventorying greenhouse gas emissions
Governments around the world are striving to hit reduction targets using Intergovernmental Panel on Climate Change (IPCC) guidelines to limit global warming.

Nitrous oxide, a greenhouse gas, is on the rise
A new study from an international group of scientists finds we are releasing more of the greenhouse gas nitrous oxide into the atmosphere than previously thought.

Atmospheric pressure impacts greenhouse gas emissions from leaky oil and gas wells
Fluctuations in atmospheric pressure can heavily influence how much natural gas leaks from wells below the ground surface at oil and gas sites, according to new University of British Columbia research.

Natural-gas leaks are important source of greenhouse gas emissions in Los Angeles
Liyin He, a Caltech graduate student, finds that methane in L.A.'s air correlates with the seasonal use of gas for heating homes and businesses

From greenhouse gas to fuel
University of Delaware scientists are part of an international team of researchers that has revealed a new approach to convert carbon dioxide gas into valuable chemicals and fuels.

UBC researchers explore an often ignored source of greenhouse gas
In a new study from UBC's Okanagan campus, researchers have discovered a surprising new source of carbon dioxide (CO2) emissions -- bicarbonates hidden in the lake water used to irrigate local orchards.

Corncob ethanol may help cut China's greenhouse gas emissions
A new Biofuels, Bioproducts and Biorefining study has found that using ethanol from corncobs for energy production may help reduce greenhouse gas emissions in China, if used instead of starch-based ethanol.

Read More: Greenhouse Gas News and Greenhouse Gas Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.