USC scientists uncover the secret of 'electric bacteria'

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A team of researchers from USC has discovered how some bacteria are able to send electric charges to objects around them -- a finding the could eventually lead to microbe-powered batteries in the future.

The organisms, called Shewanella oneidensis, grow a tendril like structure called a nanowire from their membrane and use this to send electrons to foreign surfaces as part of its process of metabolizing energy.

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Shewanella bacteria are found in the sediment beneath lakes where oxygen is sometimes in short supply.

Like most living creatures, this bacteria uses oxygen to help generate energy from the food it eats. Part of this process involves expelling electrons.

Humans and other oxygen-breathing creatures use the air we exhale to get rid of those electrons.

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However, USC researcher Moh El-Naggar says when Shewanella can't get any oxygen, it does something amazing.
"If you take away their oxygen, they will be able to breathe an external surface that is outside the cell, so it could be a rock out in the environment or in the soil," he explained.

By "breathe" El-Naggar means the bacteria use something other than oxygen to help it metabolize energy.

Shewanella does that by growing a tiny tendril from their membrane called a nanowire, El-Naggar's research team recently discovered.

The organism then uses that nanowire to touch a foreign surface, sending extra electrons there in the process. This allows it to complete its energy creating cycle.

You can see those nanowires extending from the bacteria in the video below.

A side effect of this weird work-around is that Shewanella ends up charging whatever it touched with its tendril.

"This is one of those cases where there are concrete applications," noted El-Naggar.

Specifically, he says this discovery opens up the possibility of using Shewanella to create bacteria powered batteries or microbial fuel cells in the near future.

The study was a collaboration between researchers from USC, Penn State, the University of Wisconsin-Milwaukee, Pacific Northwest National Laboratory and Rensselaer Polytechnic Institute.

It was published in the journal, "Proceedings of the National Academy of Sciences" on Monday.

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