UCLA Engineering researchers develop new method
for the production of more efficient biofuels
Left to right: Chemical and biomolecular engineering
professor James Liao,
post-doctoral fellow
Shota Atsumi and visiting
professor Taizo Hanai
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 mass production of these
biofuels.
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," Liao said. "To
modify an organism to produce these 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."
The 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.
 |
E. coli
bacteria |
"The ability to make these branched-chain
higher alcohols so efficiently is surprising," Liao said.
"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.
"Given that part of UCLA's mission is to transfer technologies
to the commercial sector to benefit the public, we are excited
at the prospect that this UCLA-developed technology may play
a key role in addressing climate change and energy independence,"
said Earl Weinstein, assistant director of the UCLA Office
of Intellectual Property. "It has been a pleasure to
work with the team at Gevo on this deal, and we look forward
to an ongoing relationship with them."
"This discovery leads to new opportunities for advanced
biofuel development," said Patrick Gruber, Gevo's chief
executive officer. "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."
Liao 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.
"Dr. Liao's input will be invaluable as we scale up
the commercial applications made possible by this breakthrough
in technology and bring advanced biofuels to market,"
said Matthew Peters, chief scientific officer of Gevo.
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 (CMISE).
###
