We’ve long known that bacteria can absorb energy from the Sun (photosynthesis) and from chemical processes (chemosynthesis), but scientists have now discovered up to ten species of electric bacteria—bacteria that are literally powered by ambient electrical energy, and may not need food or sunlight to survive. As New Scientist reports:
"Unlike any other living thing on Earth, electric bacteria use energy in its purest form – naked electricity in the shape of electrons harvested from rocks and metals. We already knew about two types, Shewanella and Geobacter. Now, biologists are showing that they can entice many more out of rocks and marine mud by tempting them with a bit of electrical juice. Experiments growing bacteria on battery electrodes demonstrate that these novel, mind-boggling forms of life are essentially eating and excreting electricity."
Scientists are hopeful that they can program bacteria to function as self-powered useful devices (SPUDs) which can perform a wide variety of valuable tasks—from cleaning up environmental contamination to building circuits, and everything in between. Solar-powered bacterial SPUDs have already been used to create sugar and lactic acid, with some success.
But the exobiology implications of electric bacteria may be the most promising of all. If scientists can successfully prove that there are species of bacteria that can subsist entirely on electrical energy (and there’s a good chance that they can), we have to entertain the possibility of electricity-based ecosystems on other planets and moons that we would not otherwise think of as habitable. And that dramatically increases not only the odds that we will discover life, but also the kinds of life that we might find.