In the episode “The Immunity Syndrome” of the original series of Star Trek, Kirk and crew encounter an 11,000-mile wide amoeba. To escape, the Enterprise must destroy the single-celled creature from the inside before it drains all the energy—the creature’s food source—from the ship. In the episode “Galaxy’s Child” of Star Trek: The Next Generation, Jean-Luc Picard and his crew must find a way to shake off a similar creature sucking energy from the Enterprise’s reactors.
Science fiction has a knack for imagining amazing organisms that defy our expectations of life. But in the last few years we’ve encountered creatures to turn this fiction into fact.
All of life is a Rube Goldberg machine moving electrons around. When you breathe you are exchanging electrons with electron-hungry oxygen. When you break down food, the excess electrons follow a complicated journey until they are eventually excreted. So living at the most basic level could be sustained through electrons alone. That’s the theory, and we’ve found the microbes to prove it.
For starters, both Shewanella, a marine bacteria, and Geobacter, a bacteria that lives without oxygen, can directly feed off electrons from marine mud, rocks, and metals. Now, a number of independent scientific teams are finding different Star Trek-style energy slurpers. At the University of Minnesota in St. Paul, for example, research has been published on microbes that can live exclusively on electrons and live their lives on electrodes. And as the data comes in, one thing is clear—these life forms are everywhere. Researchers have found these electricity breathers in wells in Death Valley and the harbors of Santa Clarita, California.
To coax the electric microbes out, scientists run currents through samples to see who comes to the dinner table. Just like Star Trek, we have to go exploring to find organisms that defy our expectations of life.