ByDavid Latchman, writer at
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David Latchman

In the Limitless episode, "Close Encounters," two astrophysicts' specially engineered bacteria that feeds on electricity takes down the New York power grid. If these two scientists, Sturgeon Reid (Jim Reid) and Ian Marshall (Robert Sella) look a lot like Bill Nye and Neil deGrasse Tyson, it is because the show's writers made it that way.

Like many of the show's episodes, the science is (somewhat) grounded in reality, as we have seen in the The Space Elevator and The Bruntouchables article. There are bacteria that can feed directly on electricity to power themselves, though the ability of seen on the show is not as dramatic.

Panspermia and the Origin of Life on Earth

If electricty eating bacteria sounds like something out of this world, it is not but it is possible to find life from outerspace. One hypothesis, mentioned in the episode, panspermia, proposes that some lifeforms can survive the harsh environment of space to eventually seed planets like ours with life. This is not intended to address how life began but, rather, how it gets distributed in the Universe.

In the TV show, the two scientist look-alikes, Marshall and Reid, make a bet of one dollar that extraterrestrial life will be found in their lifetimes. Marshall, wanting to win the bet, releases the bacteria he discovered around the time our planet passes through a comet's tail. (An entire dollar is at stake here with no bragging rights.) Comets are believed to contain the building blocks necessary for life so it is not inconceivable this is not taking place right now.

Electricity-Eating Bacteria

We are all alive because of electrons. Everyliving organism consumes sugar to survive, molecules with excess electrons. The oxygen you breathe wants those electrons. By ferrying electrons from sugar to oxygen, a flow of electrons (a current) is created. The enrgy derived from this process is then used to carry out various vital tasks around your body (triggering electrons, beating your heart, etc.)

Kenneth Nealson
Kenneth Nealson

Certain bacteria are able to do away with the middle man and feed directly on electrons. Kenneth Nealson from the University of Southern California discovered these bacteria when he stuck some electrodes in the ground and tuned on the current. He found several types of bacteria migrted to the electrons to take advantage of what is a free-food buffet.

The discovery of electron eating bacteria was not entirely new. We already knew of two types, Shewanella and Geobacter, that did this by harvesting electrons from metals and rocks. Nealson and his team is able to keep his bacteria alive with nothing but electricity. This is the equivalent of a us shoving our fingers into an electrical socket. Turns out there is some science behind Electro.

Shewanella (left) and Geobacter(right)
Shewanella (left) and Geobacter(right)

Electric bacteria also have the ability to form microbial nanowires — long chains of bacteria that can span several centimeters. The nanowires ferry nutrients to bacteria further down the chain, which might be stuck underneath some mud. These nanowires are about as conductive as standard copper wires, which could be used to build subsurface networks for us. It would be a little more efficient than spending billions of dollars on laying submarine cables.

The most obvious use for these bacteria is in the growing fields of molecular motors and nanomachines. With some clever engineering, we might use them to power tiny machines that can perform tasks currently carried out by expensive, human-operated machines (cleaning up chemical spills, for example). These bacteria might also allow us to find out exactly how much energy a living cell needs to survive; put them in a test tube, and then slowly dial back the electrode voltage until they die.

The Science of Limitless

The show gets the science premise right though, as expected, some things are changed for dramatic effect. The bacteria in the show is airborne. Electricity-eating bacteria live in the soil and are unlikely to be airborne even with genetic modification. The bacteria also would not be able to suck all the electricity from a generator and crash the New York power grid. Artistic license aside, these little critters could help us build electrical networks easier, and tiny self-powered nanomachines. Sometimes reality is cooler than fiction.


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