Scientists have genetically engineered E. coli that is
highly efficient in producing butanol, a promising new type of
biofuel.
This new technology could speed up the development of butanol biofuels into
a cost-effective alternative to ethanol.
Butanol - many attractive properties
"It [butanol] has many attractive properties," says Jim McMillan, manager
of biorefining process R&D at the National Renewable Energy Laboratory's
National Bioenergy Center, in Golden, CO. Because butanol packs more energy per
gallon than ethanol does, cars running on butanol get better mileage. And,
unlike ethanol, it doesn't mix with water, so it can be shipped in existing
petroleum pipelines without causing problems.
Several research groups are engineering microbes that can convert sugar
from various feedstocks into butanol. Most of these groups rely on the bacterium
Clostridium acetobutylicum, which naturally makes a form of butanol called
1-butanol. However, this bacterium grows slowly and is not easy to genetically
manipulate.
Manipulating E. Coli bacterium
James Liao, a chemical engineer at the University of California, and his
colleagues are looking into using E. coli. Although the bacterium does not
produce butanol naturally, it is easy to modify and grows fast. Liao says that
he can program E. coli to produce small amounts of butanol by diverting some of
the microorganism's metabolites into alcohol production. With further genetic
modifications, Liao was able to dramatically increase the efficiency of the
process. With further manipulation, the engineered microbes achieved efficiency
high enough for industrial use.
Gevo, a biofuels startup based in Pasadena, CA, has acquired an exclusive
license to commercialise Liao's technology. "It's a real breakthrough…We believe
isobutanol is a superior fuel," says Mathew Peters, Gevo's chief scientific
officer.