Biologists at the University of Southern California (USC) have discovered bacteria that survive on nothing but electricity — rather than food, they eat and excrete pure electrons. These bacteria yet again prove the almost miraculous tenacity of life.
Sugar is important to nearly all life. What we eat is converted into glucose molecules that feature excess electrons. The flow of electrons from sugar to oxygen creates the energy needed for our metabolism. (Surely, there are many variations on this model, but that’s the basic idea—producing electron flows creates energy.)
These special bacteria, however, don’t need no p[r]oxy sugars — instead, they cut out the middleman and feed directly on electrons. To discover these bacteria, and to cultivate them in the lab, the USC biologists quite simply scooped up some sediment from the ocean, took it back to the lab, stuck some electrodes into it, and then turned on the power. When higher voltages are pumped into the water, the bacteria “eats” electrons from the electrode; when a lower voltage is present, the bacteria “exhales” electrons onto the electrode, creating an electrical current (which could be used to power a device, if you were so inclined). The USC study very carefully controlled for other sources of nutrition — these bacteria were definitely eating electrons directly.
The ten varieties discovered so far are not from the same family, and are not related to Shewanella or Geobacter, which also feature “interesting electrical properties.” So this is convergent evolution.
Some electron-eating bacteria form “microbial nanowires” (see below), roughly as conductive as standard copper wires. In other words, bacteria got there long before we did.
Just by accident, of course.TM Alternatively, it is curious how life forms exploit virtually every strategy for staying alive. Yet non-life does not exploit any strategy to preserve itself nor seek to become life.
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