“It shouldn’t be possible. Those things just keep growing on the electrode, and there’s no other source of energy there.” Growing on the electrode. It sounds incredible. “It is kind of like science fiction”. To a biologist, finding life that chugs along without a molecular energy source such as carbohydrates is about as unlikely as seeing passengers flying through the air without an airplane.

2016-06-22: Now with a mechanism

one of the most exciting possibilities is finding life-forms that might survive in extreme environments. Mars, for example, is iron-rich and has water flowing beneath its surface. If you have a system that can pick up electrons from iron and have some water, then you have all the ingredients for a conceivable metabolism. Perhaps a former mine 1600m underneath South Dakota won’t be the most surprising place that researchers find electron-eating life. The microbes’ apparent ability to ingest electrons — known as direct electron transfer — is particularly intriguing because it seems to defy the basic rules of biophysics. The fatty membranes that enclose cells act as an insulator, creating an electrically neutral zone once thought impossible for an electron to cross.

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