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Professor Jeffrey Gralnick, of the University of Minnesota's BioTechnology Institute and department of microbiology, helped to lead the effort that discovered Vitamin B-2's role in upping Shewanella's eletrical output.  (Source: University of Minnesota)

Shewanella, shown here in blue, was also found by separate researchers to be capable of producing carbon nanotubes, shown in yellow.  (Source: University of California Riverside)
It turns out mom was right, when she told you to take your vitamins.

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 purifying water, to data storage, to microbial biofuel and hydrogen production.

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 be governed.

Researchers at the University of Minnesota have now 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.

The 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 levels.

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."

The 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.

For 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 earth."

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 technology further. 

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 project. 

The very useful Shewanella bacterium has also been found to produce carbon nanotubes under the proper conditions.



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RE: hold on a second
By jtemplin on 3/6/2008 2:42:22 AM , Rating: 2
Here is what it needs to grow on:
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

Re: how much electricity
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).


I think you folks who are worried about bacteria mutating and killing people need to stop spewing ignorance and enroll in your local community college's microbiology course. You might learn something! With that said, this organism is an opportunistic pathogen and by my meager research has 2 documented cases of infection. I really doubt there is anything to fear from this organism.

For example: decomposition of all kinds is mediated by bacteria and this happens and has happened for millions of years without any human input. I don't think the primary industrial usage of this bacteria would be in decomposing solid garbage. Maybe in treating waste water. But also consider that these bacteria are versatile (facultative anaerobes) and microbiologists can actually culture them. For example: The bacteria causing leprosy (M. leprae) has never been cultured on laboratory media (in vitro) The fact that a bacteria using an exotic type of metabolism can be grown in a lab is a big plus.

Another reason scientists are interested in these bacteria is because they can use uranium as their terminal electron receptor and reduce it to a form that is insoluble. This represents a form of bioremediation which could be used to protect or clean aquifers from radio-contaminants. This research is also important because it shows that something as simple as adding an electron acceptor for this bacteria can increase output by 370%.

I will attempt to clarify/correct the articles description of what the bacteria is doing to generate electricity.

quote:
The bacteria needs to digest certain soil metals such as iron to survive and thrive.
Iron is used by this bacteria as the terminal electron acceptor in their electron transport chain. Basically in respiration you need to get ATP, and you have (simplified model here) glycolysis-->krebs(TCA)-->electron transport chain. The first two don't produce much ATP but they reduce electron acceptors (reduce means taking electrons--counterintuitive yes) such as NAD and FAD which become NADH and FADH2. These middle men electron acceptors pass electrons down the chain to the terminal acceptor. Note: terminal electron receptor is a consumable. For most eukaryotes this acceptor is oxygen. We wouldn't say we are digesting oxygen would we? What the bacteria is "digesting" is the carbon source which supplies the electrons or H+. I felt the description was a bit lacking and needed clarification.
quote:
In order to properly absorb them it directs electrons into the metals to change their properties, making them more digestible.
The utility of riboflavin here is two fold. First, riboflavin is directly shuttling electrons in their transport chain. Second, Riboflavin can chelate certain metal ions. Chelating refers to the ability of an organic compound to bind metals ion which become less reactive. This packages the iron in a form that the cell can use. So by adding a needed intermediate in their respiration process that also helps procure more terminal electron acceptor, the electrical output (which is an objective measure of their rate of metabolism) is optimized.

/end book writing

Sources:
Original Press Release
quote:
http://www1.umn.edu/urelate/newsservice/NS_details...


Shewanella secretes flavins that mediate extracellular electron transfer

Enrico Marsili, Daniel B. Baron, Indraneel D. Shikhare, Dan Coursolle, Jeffrey A. Gralnick, and Daniel R. Bond,
quote:
http://www.pnas.org/cgi/content/abstract/071052510...


Effects of aqueous complexation on reductive precipitation of uranium by Shewanella putrefaciens

Johnson R Haas and Abraham Northup
quote:
http://www.pubmedcentral.nih.gov/articlerender.fcg...


RE: hold on a second
By jtemplin on 3/6/2008 11:33:08 PM , Rating: 2
I hope someone read this lol...


RE: hold on a second
By jlips6 on 3/8/2008 5:41:21 PM , Rating: 2
I've studied microbiology and how microorganisms function, but this when right over my head. I understood some stuff, but when it went beyond talking about how you react atp with other things, my eyes glazed over.


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