Researchers modify E. coli to produce efficient higher-chain alcohol biofuels
Researchers at the UCLA Henry Samueli School of Engineering and Applied Science have developed a new method for producing next-generation biofuels by genetically modifying Escherichia coli bacteria to be an efficient biofuel synthesizer. The method could lead to the mass production of higher-chain alcohol-based biofuels like butanol and isobutanol, which are more efficient than ethanol. The technology has been licenced to Gevo Inc., a next-generation biofuel company supported by Khosla Ventures and the Virgin Green Fund.
The strategy, developed by UCLA professor of chemical and biomolecular engineering James Liao, postdoctoral fellow Shota Atsumi and visiting professor Taizo Hanai, appears in the Jan. 3 issue of the journal Nature.
Concerns about long-term fossil fuel availability, coupled with environmental problems resulting from their production and use, have spurred increased efforts to synthesize biofuels from renewable resources.
Biofuels, like commercially available ethanol, are produced from agricultural products such as corn, sugarcane or waste cellulose. Ethanol, however, has limitations — it is not as efficient as gasoline and must be mixed with gas for use as a transportation fuel. It also tends to absorb water from its surroundings, making it corrosive and preventing it from being stored or distributed in existing infrastructure without modification.
Higher-chain alcohols have energy densities close to gasoline, are not as volatile or corrosive as ethanol, and do not readily absorb water. Furthermore, branched-chain alcohols, such as isobutanol, have higher-octane numbers, resulting in less knocking in engines. Isobutanol or C5 alcohols have never been produced from a renewable source with yields high enough to make them viable as a gasoline substitute.
This strategy leverages the E. coli host's highly active amino acid biosynthetic pathway by shifting part of it to alcohol production. In particular, the research team achieved high-yield, high-specificity production of isobutanol from glucose. This new strategy opens an unexplored frontier for biofuels production, both in coli and in other microorganisms:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: ethanol :: biobutanol :: isobutanol :: biosynthesis :: bioconversion :: biotechnology ::
The ability to make these branched-chain higher alcohols so efficiently is surprising. Unlike ethanol, organisms are not used to producing these unusual alcohols, and there is no advantage for them to do so. The fact that they can be made by E. coli is even more surprising, since E. coli is not a promising host to tolerate alcohols. These results mean that these unusual alcohols in fact can be manufactured as efficiently as what evolved in nature for ethanol. Therefore, we now can explore these unusual alcohols as biofuels and are not bound by what nature has given us.
UCLA has licensed the technology through an exclusive royalty-bearing license to Gevo Inc., a Pasadena, Calif.-based company founded in 2005 and dedicated to producing biofuels. The company is supported both by Vinod Khosla's Khosla Ventures and Richard Branson's Virgin Green Fund.
The research was supported in part by the UCLA–Department of Energy Institute for Genomics and Proteomics and the UCLA–NASA Institute for Cell Mimetic Space Exploration.
Schematic: Gevo's bio-butanol production process. Credit: Gevo Inc.
References:
Shota Atsumi, Taizo Hanai & James C. Liao, "Non-fermentative pathways for synthesis of branched-chain higher alcohols as biofuels", Nature, 451, 86-89 (3 January 2008), doi:10.1038/nature06450
UCLA: UCLA researchers develop method for production of more efficient biofuels - January 2, 2007.
The strategy, developed by UCLA professor of chemical and biomolecular engineering James Liao, postdoctoral fellow Shota Atsumi and visiting professor Taizo Hanai, appears in the Jan. 3 issue of the journal Nature.
Concerns about long-term fossil fuel availability, coupled with environmental problems resulting from their production and use, have spurred increased efforts to synthesize biofuels from renewable resources.
Biofuels, like commercially available ethanol, are produced from agricultural products such as corn, sugarcane or waste cellulose. Ethanol, however, has limitations — it is not as efficient as gasoline and must be mixed with gas for use as a transportation fuel. It also tends to absorb water from its surroundings, making it corrosive and preventing it from being stored or distributed in existing infrastructure without modification.
Higher-chain alcohols have energy densities close to gasoline, are not as volatile or corrosive as ethanol, and do not readily absorb water. Furthermore, branched-chain alcohols, such as isobutanol, have higher-octane numbers, resulting in less knocking in engines. Isobutanol or C5 alcohols have never been produced from a renewable source with yields high enough to make them viable as a gasoline substitute.
These alcohols are typically trace byproducts in fermentation. To modify an organism to produce saidthese compounds usually results in toxicity in the cell. We bypassed this difficulty by leveraging the native metabolic networks in E. coli but altered its intracellular chemistry using genetic engineering to produce these alcohols. - James LiaoThe research team modified key pathways in E. coli to produce several higher-chain alcohols from glucose, a renewable carbon source, including isobutanol, 1-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol and 2-phenylethanol.
This strategy leverages the E. coli host's highly active amino acid biosynthetic pathway by shifting part of it to alcohol production. In particular, the research team achieved high-yield, high-specificity production of isobutanol from glucose. This new strategy opens an unexplored frontier for biofuels production, both in coli and in other microorganisms:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: ethanol :: biobutanol :: isobutanol :: biosynthesis :: bioconversion :: biotechnology ::
The ability to make these branched-chain higher alcohols so efficiently is surprising. Unlike ethanol, organisms are not used to producing these unusual alcohols, and there is no advantage for them to do so. The fact that they can be made by E. coli is even more surprising, since E. coli is not a promising host to tolerate alcohols. These results mean that these unusual alcohols in fact can be manufactured as efficiently as what evolved in nature for ethanol. Therefore, we now can explore these unusual alcohols as biofuels and are not bound by what nature has given us.
UCLA has licensed the technology through an exclusive royalty-bearing license to Gevo Inc., a Pasadena, Calif.-based company founded in 2005 and dedicated to producing biofuels. The company is supported both by Vinod Khosla's Khosla Ventures and Richard Branson's Virgin Green Fund.
This discovery leads to new opportunities for advanced biofuel development. As the exclusive licensee of this technology, we can further our national interests in developing advanced renewable resource-based fuels that will help address the issues of climate change and future energy needs while creating a significant competitive advantage. - Patrick Gruber, Gevo chief executive officerLiao has joined Gevo's scientific advisory board. In this role, he will continue to provide technical oversight and guidance during the commercial development of this technology.
The research was supported in part by the UCLA–Department of Energy Institute for Genomics and Proteomics and the UCLA–NASA Institute for Cell Mimetic Space Exploration.
Schematic: Gevo's bio-butanol production process. Credit: Gevo Inc.
References:
Shota Atsumi, Taizo Hanai & James C. Liao, "Non-fermentative pathways for synthesis of branched-chain higher alcohols as biofuels", Nature, 451, 86-89 (3 January 2008), doi:10.1038/nature06450
UCLA: UCLA researchers develop method for production of more efficient biofuels - January 2, 2007.
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