Skip to main content

Posts

Showing posts from March, 2009

Part III: Dissimilatory Bacteria in Uranium Reduction

Last time, we explored how dissimilatory bacteria can be used to generate electricity in devices called Microbial Fuel Cells. In part one, I mentioned that the dissimilatory properties of bacteria like Shewanella can potentially also be used for solving part of the problem of radioactive uranium contaminations. When I mentioned this idea to my friend who is a soil scientist, I realized that I did not know how these bacteria can be used to contain uranium contamination. Curious about how exactly this works, I found a review article titled “Uranium Reduction” in the Annual Review of Microbiology written by Judy D. Wall and Lee R. Krumholz (Vol. 60: 149-166, Oct 2006). Following is a summary of what I found.

Uranium is a metal with the symbol U on the periodic table. It has the atomic number 92 which means that it has 92 protons and electrons. In nature, occurs in three different forms U-238 (~ 99.238 %), U-235 (0.711 %), and U-234 (0.0058%) where each number refers to the combined numbe…

Part II: Microbial Fuel Cells (MFC)

I can’t believe how fast time passes. I have been meaning on writing this post up for a long time now. In the last post, I just was introducing Shewanella onedeinensis and its ability to transfer electrons from a variety of organic substrates to metal oxides. Today, we shall look at one possible application for such a microbe: using bacteria to make electricity.

This is done through contraptions called Microbial Fuel Cells (MFCs) but to understand MFCs we need to first understand how fuel cells work. There is going to be some detail. But the take-home message here though is: We can use certain bacteria to make electricity out of waste.

A fuel cell is a device that produces electricity as long as one provides an external source of fuel and a source that accepts electrons known as oxidants. This is different from normal batteries because batteries simply release the electrical energy stored within them. They get tossed once they are used up. In the case of rechargeable batteries, energy…