COLLEGE
STATION, Texas--For most people, the name "E. coli" is synonymous with
food poisoning and product recalls, but a professor in Texas A&M University's
chemical engineering department envisions the bacteria as a future source
of energy, helping to power our cars, homes and more.
By genetically modifying the bacteria,
Thomas Wood, a professor in the Artie McFerrin Department of Chemical Engineering,
has "tweaked" a strain of E. coli so that it produces substantial amounts
of hydrogen. Specifically, Wood's strain produces 140 times more hydrogen
than is created in a naturally occurring process, according to an article
in "Microbial Biotechnology," detailing his research.
Though Wood acknowledges that there
is still much work to be done before his research translates into any kind
of commercial application, his initial success could prove to be a significant
stepping stone on the path to the hydrogen-based economy that many believe
is in this country's future.
Renewable, clean and efficient, hydrogen
is the key ingredient in fuel-cell technology, which has the potential
to power everything from portable electronics to automobiles and even entire
power plants. Today, most of the hydrogen produced globally is created
by a process known as "cracking water" through which hydrogen is separated
from the oxygen. But the process is expensive and requires vast amounts
of energy - one of the chief reasons why the technology has yet to catch
on.
Wood's work with E. coli could change
that.
While the public may be used to hearing
about the very specific strain that can cause food poisoning in humans,
most strains are common and harmless, even helping their hosts by preventing
other harmful bacteria from taking root in the human intestinal tract.
And the use of E. coli in science
is nothing new, having been used in the production of human insulin and
in the development of vaccines.
But as a potential energy source?
That's new territory, and it's being
pioneered by Wood and his colleagues.
By selectively deleting six specific
genes in E. coli's DNA, Wood has basically transformed the bacterium into
a mini hydrogen-producing factory that's powered by sugar. Scientifically
speaking, Wood has enhanced the bacteria's naturally occurring glucose-conversion
process on a massive scale.
"These bacteria have 5,000 genes
that enable them to survive environmental changes," Wood explained. "When
we knock things out, the bacteria become less competitive. We haven't given
them an ability to do something. They don't gain anything here; they lose.
The bacteria that we're making are less competitive and less harmful because
of what's been removed."
With sugar as its main power source,
this strain of E. coli can now take advantage of existing and ever-expanding
scientific processes aimed at producing sugar from certain crops, such
as corn, Wood said.
"A lot of people are working on converting
something that you grow into some kind of sugar," Wood explained. "We want
to take that sugar and make it into hydrogen. We're going to get sugar
from some crop somewhere. We're going to get some form of sugar-like molecule
and use the bacteria to convert that into hydrogen."
Biological methods such as this (E.
coli produce hydrogen through a fermentative process) are likely to reduce
energy costs since these processes don't require extensive heating or electricity,"
Wood said.
"One of the most difficult things
about chemical engineering is how you get the product," Wood explained.
"In this case, it's very easy because the hydrogen is a gas, and it just
bubbles out of the solution. You just catch the gas as it comes out of
the glass. That's it. You have pure hydrogen."
There also are other benefits.
As might be expected, the cost of
building an entirely new pipeline to transport hydrogen is a significant
deterrent in the utilization of hydrogen-based fuel cell technology. In
addition, there is also increased risk when transporting hydrogen.
The solution, Wood believes, is converting
hydrogen on site.
"The main thing we think is you can
transport things like sugar, and if you spill the sugar there is not a
huge catastrophe," Wood said. "The idea is to make the hydrogen where you
need it."
Of course, all of this is down the
road. Right now, Wood remains busy in the lab, working on refining a process
that's already hinted at its incredible potential. The goal, he said, is
to continue to get more out of less.
"Take your house, for example," Wood
said. "The size of the reactor that we'd need today if we implemented this
technology would be less than the size of a 250-gallon fuel tank found
in the typical east-coast home. I'm not finished with this yet, but at
this point if we implemented the technology right now, you or a machine
would have to shovel in about the weight of a man every day so that the
reactor could provide enough hydrogen to take care of the average American
home for a 24-hour period.
"We're trying to make bacteria so
it doesn't require 80 kilograms; it will be closer to 8 kilograms."
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