Bacteria have been a hot topic in research these days. It
turns out that the little guys, oft
vilified for their pathogenic brethren, can provide exciting
solutions to many alternative energy and material purification
problems. Researchers have used bacteria for everything from
water, to data
storage, to microbial
biofuel and hydrogen
Now researchers have made an exciting new
microbiological breakthrough involving a very special type of
bacteria. It has been known for some time that the bacteria,
Shewanella, found commonly in water and soil, produces electricity
when it digests organic matter. This led to researchers taking
special interest in its potential as a natural generator.
However, a major roadblock to such alternative energy plans was the
fact that it was unknown until now is exactly how the bacteria
accomplished its electrical generation, or whether the process could
Researchers at the University of Minnesota have
discovered that the vitamin riboflavin (known commonly as vitamin
B-2), provides the bacteria with much of its generating
capabilities. The research was led by Daniel Bond and Jeffrey
Gralnick, of the University of Minnesota's BioTechnology Institute
and Department of Microbiology.
Professor Bond explained the
importance of their discovery, stating, "This is very exciting
because it solves a fundamental biological puzzle. Scientists
have known for years that Shewanella produce electricity. Now we know
how they do it."
Their research, which will be published
in the March 3 issue of the “Proceedings of the National Academy of
Sciences” opens the door to an exciting new chapter in alternative
energy. By boosting the Shewanella bacteria's riboflavin intake
with vitamins, the bacteria's electrical output dramatically
increases. These bacteria can transform organic waste
byproducts such as lactic acid into electricity, offering both a
waste disposal and an alternative energy solution.
research team discovered riboflavin's effects when bacteria growing
on their electrodes began to increase in electrical output. The
team discovered that the increase was do to the accumulation of
riboflavin on the electrodes, a substance the bacteria naturally
produce. As the riboflavin built up, the bacteria's electrical
output increased to a maximum of 370 percent of the original
Potential uses include waste water microbial fuel
cells and, according to researchers, a natural fuel source for ocean
floor probes. Professor Bond remarks, "Bacteria could help
pay the bills for a wastewater treatment plant."
researchers do warn that in order for the technology to be
cost-effective for home and business use or for transportation,
significant biological and fuel cell design obstacles would have to
be overcome. For now, the technology provides a great deal of
niche potential for the waste water industry, they say.
those curious of why Shewanella outputs electrical current, here's
why. The bacteria needs to digest certain soil metals such as
iron to survive and thrive. In order to properly absorb them it
directs electrons into the metals to change their properties, making
them more digestible. Says Profesor Gralnick, "Bacteria
have been changing the chemistry of the environment for billions of
years. Their ability to make iron soluble is key to metal
cycling in the environment and essential to most life on
Such bacteria could also be applied to ship
surfaces and used in a reverse process to prevent corrosion by
outputting iron. The U.S. Navy is interested enough in this
application to provide the team with a grant to explore the
The research was primarily funded
by the Initiative for Renewable Energy and the Environment, the
National Science Foundation, the National Institutes of Health and
Cargill. The University of Minnesota's College of Biological
Sciences and the Institute of Technology were also involved with the
The very useful Shewanella bacterium has also been found to
carbon nanotubes under
the proper conditions.
quote: Medium contained (per liter): 0.46 g NH4Cl, 0.225 g K2HPO4, 0.225 g KH2PO4, 0.117 g MgSO4 7 H2O, 0.225 (NH4)2 SO4, plus 10 ml of a mineral mix (containing per liter: 1.5 g NTA, 0.1 g MnCl2_4H2O, 0.3 g FeSO4_7H2O, 0.17 g CoCl2_6H2O, 0.1 g ZnCl2, 0.04 g CuSO4_5H2O, 0.005 g AlK(SO4)2_12H2O, 0.005 g
quote: ...expressed per unit electrode surface area, rates obtained with Shewanella (0.15 A/m2) remain many orders of magnitude lower than what is obtained in chemical fuel cells (1,000 A/m2), similar to what has been observed for other microbial catalysts (13, 33).
quote: The bacteria needs to digest certain soil metals such as iron to survive and thrive.
quote: In order to properly absorb them it directs electrons into the metals to change their properties, making them more digestible.