Bacteria Found to Use Their Own Natural Battery

By Quinn Fucile | Mar 30, 2015 03:36 PM EDT

Humans love inventing things, it's one of the things that actually separates us from other animals on this planet. Arguably one of our greatest inventions was electricity, it's what makes our modern civilization possible.

Still in an abstract sense, we've known for a long time that life is essentially electrical. Sure most organisms eat sugar and use ATP to actually exchange energy, but metabolism itself is primarily a flow of electrons. Surely though that is nothing compared to our electricity, with generators, power lines, and batteries, right?

At least in the battery department, it would appear that bacteria beat us to the punch a long long time ago. As reported on EurekaAlert, a team from the University of Tübingen, the University of Manchester, and Pacific Northwest National Laboratory; recently discovered a bacteria species that can utilize a kind of natural battery. Unfortunately, it doesn't appear that this discovery could improve our batteries, unlike many molecular machines in nature. It does however bring up some other interesting possibilities.

For a while scientists have known about bacteria that can essentially eat metal. They use iron are other naturally occurring metallic compounds as a donor or acceptor of electrons within their metabolism. But this recent discovery is the first evidence of a metal acting as a battery for a living organism.

In this instance it was magnetite, a common and naturally occurring iron oxide. And the bacteria was a soil dwelling purple bacteria that is also phototrophic. This means that sunlight is naturally part of their metabolism, but in a different way than conventional photosynthesis like found in algae and plants. The battery like behavior was only found when culturing the bacteria with magnetite, and replicating a natural day-night cycle.

During the day this primary purple bacteria would oxidize the magnetite as part of its metabolism, removing electrons from the material. At night, different bacteria would take over and actually pump electrons back into the magnetite. What the researchers found was this cycle of discharging and recharging happening over and over again with the same magnetite.

They're curious whether these bacteria could use other kinds of metal in this cycling process, or whether this mechanism could be incorporated into other bacteria. It may have uses in environmental clean-up. Toxic metals such as chromium can be sequestered through reduction-oxidation reactions like these bacteria naturally perform. This electronic exchange mechanism could also find other interesting chemical applications. 

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