Bacteria can clean up toxins, oil spills and nuclear waste, essentially by eating the stuff. But until now nobody was quite sure how they did it. Gemma Reguera and her team at Michigan State University found that the key is a structure called the pilus, a hair-like appendage that acts like a wire.

The bacteria, called Geobacter sulfurreducens, transfer electrons via the pilus to the metals that they feed off of. Transferring the electrons gives the bacteria energy. It also changes the ionization state of the metal, changing it to a form that precipitates out of water. A colony ofGeobacter living near a pile of nuclear waste would extract the uranium, making it easier to handle and remove.