Some Bacteria Can Live on Electricity

Some bacteria can survive by taking electrons from metals or minerals, letting them live in places where ordinary food is scarce.

Biology

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Some bacteria have an unusually flexible way of getting energy: they can move electrons to or from metals and minerals outside their cells. One well-studied example, Shewanella oneidensis, can transfer electrons from inside the cell onto metal compounds such as manganese oxide, while other microbes can take electrons from solid materials or electrodes. Scientists describe these processes as extracellular electron transfer. Certain microbes studied from ocean-floor environments have even shown the ability to grow using electrical energy with little or no conventional carbon food source, depending on the exact organism and growth conditions. This does not mean bacteria simply eat electricity in the everyday sense. They still require the materials needed to build and maintain cells, but electrical electrons can serve as an unusual source of energy or reducing power. These microbes are especially interesting because deep sediments and underground environments can be poor in conventional food while still containing useful electrical gradients and mineral surfaces. Their unusual metabolism also matters beyond basic biology. Electroactive microbes are being studied for microbial fuel cells, environmental processes, and other forms of bioelectrochemistry. The broader significance is that life can exploit energy pathways that look very different from the familiar food-and-oxygen model, expanding the range of environments scientists consider potentially habitable.

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