—
Will soldiers someday wear vests containing microbes that
signal contact with biological weapons? Could un-manned
submarines or underwater sensing devices run on
microbe-power?
Research
conducted by University of Massachusetts microbiologists and
reported in this week’s issue of the journal Science
concludes that certain microorganisms can transform organic
matter commonly found at the bottom of the ocean into
electrical energy. Aside from raising the possibility that
microbes someday could be used to produce power in
subsurface settings, the findings have implications for many
industrial and military applications, according to Derek R.
Lovley, UMass microbiologist and team leader. An
understanding of how microbes generate and use electrical
energy may also prompt the development of new technologies
to decontaminate polluted water and sediment containing
organic materials, including petroleum and other aromatic
hydrocarbons, he says.
In the
Science article, Lovley explains how the team used water and
sediment from Boston Harbor, a collection of mason jars,
ordinary electrical wiring, and sterile graphite electrodes
to determine the science behind the mechanics of a simple,
sediment battery. The researchers added a layer of common
mud to water in the jars, put one graphite electrode in the
mud, another in overlying water. The resulting electrical
current was strong enough to activate a lightbulb, or a
simple computer. “Even using a primitive electrode made
from graphite,” Lovley said, “it is possible to produce
enough current to power basic electronic marine
instruments.”
Through more refined experiments, Lovley’s group found
that a family of energy-harvesting microorganisms, commonly
referred to as Geobacters, were key to the production of the
electrical current. Whereas most life forms, including
humans, get their energy by oxidizing organic compounds with
oxygen, Geobacters can grow in environments lacking oxygen
by using the iron naturally present in soil, in place of
oxygen. This new research demonstrates that Geobacters can
also substitute an unnatural substance, such as an
electrode, for the iron, according to Lovley.
A large
number of a Geobacter species known as Desulfuromonas
acetoxidans (D. acetoxidans) were found on the anode end of
the primitive batteries. When the researchers destroyed the
D. acetoxidans in the sediment, the current stopped.
“In the
mud, a community of microorganisms cooperates to break down
larger, more complex organic compounds to acetate.
Geobacters then transfer the electrons from the acetate to
the electrode generating the electrical energy,” he said.
Lovley’s
group also has found that some Geobacters can convert toxic
organic compounds, such as toluene, to electricity. Lovley
says this suggests that some Geobacters can be used to
harvest energy from waste matter, or can be included in
technology used to clean up subsurface environments
contaminated by organic matter, especially petroleum.
Earlier studies had shown bacteria could produce electricity
under artificial conditions in which special chemicals were
added, but the UMass study was the first to prove that the
nearly ubiquitous microbes living in a typical marine
environment could produce electricity under the conditions
naturally found in that environment.
“Once we
know more about the genome of Geobacters, we will be able to
manipulate these organisms to make them receptive to a
variety of organic or inorganic contaminants. Theoretically,
when they begin to degrade the contaminant, they will throw
electrons on an electrode, and that could set off a light, a
sound or some other form of signal,” Lovley said. “An
understanding of how this phenomenon operates has a number
of extremely timely applications, especially in developing
technologies to recognize toxins and organic
contaminants.” Lovley cites, for example, the potential
for using such technology to develop military equipment that
could alert soldiers to the presence of toxins or biological
warfare agents in the immediate environment.
The
Office of Naval Research funded this study. The research
team included Daniel R. Bond and Dawn E. Holmes from UMass,
and Leonard M. Tender of the Naval Research Laboratories.
-30-
From
University of Massachusetts
Thursday, January 17, 2002
.gif){kind=small}
