The term “electric bacteria” may bring a lot of images to mind — maybe a post-apocalyptic scenario where electrified bacteria doom our species to extinction. But the reality is more benign and potentially revolutionary.
“[Electric bacteria] harvest the energy by harvesting the electrons from whatever they’re eating, and instead of using the electron energy, the electric energy to grow faster, they can use it to export the electrons to the outside,” said Dr Ken Nealson. He discovered Shewanella oneidensis, the first identified electric bacteria.
This discovery was spurred by a question about the metal content of Oneida Lake in New York, and has since evolved into a new field of research that’s changed the concept of biofuel and could alter the future of energy production. Nealson explained that when these bacteria in Oneida Lake exported these electrons to rocks, they would dissolve the minerals, removing these metals from the water. He later learned they could replace the rocks with an electrode — a conductor for electricity.
“The bacteria swim up to that electrode, they eat whatever you give them to eat, and they pass the electrons. Basically, they’re using the electrode as an oxygen substitute … Now, if you just put that in a device, you can feed the bacteria on one side of the fuel cell and all the electrons go to the other side,” which will power the device,” Nealson explained.
This has resulted in microbial fuel cells which create energy, while simultaneously purifying wastewater. Nealson said that if the right bacteria are identified, they can handle all kinds of waste, including human and animal sewage.
“Bacteria can eat all these kinds of nasty things that we call pollution. And that’s what they do for a living, they eat almost any kind of organic material, including human waste water,” he explains.
Nealson said the uses for these bacteria seem endless. Some have been able to eat and purify water containing uranium and selenium. Some scientists believe these bacteria may allow us to colonize Mars.
When Nealson first identified Shewanella oneidensis, many scientists didn’t think it was possible for these bacteria to exist. Now, he said that turned out to be a blessing.
“The really great thing that happens when you publish something that’s a little bit controversial, is everyone who doesn’t believe it tries to repeat it and show you’re wrong. And then when they repeat it and show you’re right, they become your colleagues,” he said.
Now, there are many researchers working with these bacteria, including one of his former students. Orianna Bretschger’s company Aquacycl is creating large-scale microbial fuel cells for industrial, commercial, and agricultural purposes.