Powering Up...With A Microbial Fuel Cell

Reporting in Environmental Science and Technology, researchers write of harvesting electricity from microbe-rich river sediments—enough to power a small LED bulb. Grant Burgess, a marine biotechnologist at Newcastle University, discusses the hunt for electron-burping bugs.

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IRA FLATOW, HOST:

You're listening to SCIENCE FRIDAY. I'm Ira Flatow. What if you could light up a streetlight just by plugging it into the ground, using bacteria in the soil to power it? Sounds a little crazy or sci-fi. But my next guest has actually done something very similar, building a fuel cell that uses bacteria to generate electricity. And it pumped out enough juice to power a small LED bulb. This isn't some new breed of genetically engineered bugs from the lab. You can find these bacteria just by scooping up some river mud as our researchers did.

So why not harness the millions of trillions of bacteria out there to help out with our electricity needs? And how close are we to scaling this up from microbial fuel cells to microbial power plants? Grant Burgess is a professor of marine biotechnology at Newcastle University in the U.K. He is author of a study out this week in the journal Environmental Science and Technology. He joins us by phone. Welcome to SCIENCE FRIDAY, Dr. Burgess.

DR. GRANT BURGESS: Good afternoon, Ira. It's a pleasure to be on your show.

FLATOW: Well, thank you very much. How do you get electricity from bacteria? How simple is it?

BURGESS: Well, it's an amazing phenomenon, actually. And as you said earlier, it's also a well-known phenomenon. In fact, Professor Michael Potter first described this as far back as 1911. And he showed that bacteria could be used to generate electrons and that those electrons could be captured onto an electrode to create an electrical current.

FLATOW: We had a researcher a couple of years ago - well, actually, in 2010, from the U.S. Naval Research Lab, and she had found mud in the Potomac that you stuck probes into it and it generated electricity.

BURGESS: That's right, that's right. I mean, in a sense it's similar to the way you and I would obtain electricity from eating, you know, eating a chocolate bar. You know, the chemical energy is converted by the metabolism in your cell to a load of electrons, and you know, in your own body. Those electrons are converted into the energy-generating molecule ATP, whereas in bacteria we can actually harvest those electrons and use them ourselves. You know, we can capture them and use them as a source of electricity. So it's really quite exciting.

FLATOW: What's also quite interesting about your research is the name of the bacterium that you...

(SOUNDBITE OF LAUGHTER)

FLATOW: Yes, indeed. I'll just read them out, actually, because the names are lovely: Bacillus stratosphericus and Bacillus altitudinis. And amazingly, although we found these bacteria, as you said, in estuarine mud in the northeast of England, they were actually first observed and first isolated approximately 25 miles up in the upper stratosphere of the Earth.

Wow. So they were floating around up there and settling down or vice versa? Coming up from the mud or...

BURGESS: It's a very good question, actually. I think I would have to suggest that they probably came from the Earth and went upwards. The interesting thing about that height is you're also about 10 to 12 miles above the ozone layer. And, of course, that means that above that you've got a lot of UV radiation. And these bacteria seem to be very resistant to ultraviolet, which is another interesting property of them. But our work shows that they, you know, they may well be more widespread than was previously thought.

FLATOW: And that raises all kinds of questions. Let me ask you this one. So your samples came from the mud, and they came from a marine environment? Is that correct?

BURGESS: That's right. We - I mean, I've been interested in marine bacteria for many years because of their great diversity. And what we did - in fact, what a student of mine did is he took a sample from estuary mud from the River Wear, which is a river in the northeast of England. And we brought that mud back to the lab and set up a microbial fuel cell with my colleague Professor Keith Scott, who is an expert on microbial fuel cells. And it was kind of interesting.

Initially, it just stayed in the lab and didn't do anything for a couple of weeks. And then very slowly it started to generate electricity as the bacteria adapted to that environment. So it was quite exciting to see the current starting to increase, you know, after a couple of weeks of it just looking like it wasn't going to work. So it's very exciting.

FLATOW: Mm-hmm. And you made enough electricity that you could light up a little light emitting diode bulb with it.

BURGESS: That's right. I mean obviously we have experimental fuel cells like this. I mean the electrode is just a couple of inches by a couple of inches. So these are very small experimental electrodes, and in general they produce relatively small amounts of electricity. And to put it into some kind of context that your listeners might understand, it's probably about 100th the electrical power of, say, a car battery, something like that.

FLATOW: That's still pretty good. One hundred...

BURGESS: Absolutely.

FLATOW: Yeah.

BURGESS: You know, one of the ways to improve that is to actually have a lot of these systems in series, and you can actually increase the power that you would be able to gain from them.

FLATOW: Is this bacterium pretty good at what it does? Is it better than others of its kind of making electricity?

BURGESS: Sure. I mean, one of the interesting things about our study is that as a microbiologist, I'm very interested in bacterial slime, if you will. And we were trying to analyze exactly which species of bacteria where in this - growing on this electrode, there's a layer of slime actually producing the electricity. So what we did is we separated out about 70 different species of bacteria, and then we individually checked each one to see how much electricity it was making. And, you know, the winner by far and away, with about 10 times the electrical - electricity producing power of all the others was this bacillus stratosferica. So there's something very unusual about it that we're currently studying.

FLATOW: Mm-hmm. Do you imagine there might be others that are unfound, yet to be discovered?

BURGESS: Absolutely. I mean, I think, if there's one thing that's clear, it's that there are a vast number of bacteria, which we, you know, we don't even know how to grow them in the laboratory. And yet, genetic tools tell us that they are there, so you can, kind of, tantalizingly see fingerprints of them using molecular techniques. But we don't how to grow them in the lab and therefore we can't study them very well. And so another exciting aspect of our study is that we actually grew these in the lab and, you know, we were able to study them subsequently.

FLATOW: So you were lucky because, as you say, what - 90 percent of bacteria in the world can't be grown in the laboratory.

BURGESS: That's right. That's right. And it's very frustrating if you're a microbiologist.

(SOUNDBITE OF LAUGHTER)

FLATOW: But, you know, as a microbiologist, aren't you sort of tempted to tinker with the inner-workings of the bacterium and say, I can genetically engineer a better one now that I have this one?

BURGESS: Well, I mean, I think, that - I mean, certainly was of that opinion, you know, a long time ago, in the 1980s and early 1990s. But the more you look at the bacteria that are out there in nature, the more you realize that in fact they're pretty good at what they do. I mean, they've been around on the planet Earth for about 300 and a bit billion years. And so they have been, you know, they've been around and they've been able to perfect these processes really quite well. And so it's very difficult to, you know, actually try to engineer improvements with any great accuracy. So I'm a great believe in searching for naturally occuring bacteria that already do what you want them to do, if you see what I mean.

FLATOW: Yeah. A couple of questions for you. When might we see some practical application come out of the bacteria? Can you...

BURGESS: Well, I mean, it was interesting, in your introductory remarks you said it might be possible one day to kind of put a stick in the ground and it would extract electricity from the soil. You know, a couple of scientists a few years ago have already done that, amazingly, by putting a fuel cell into some marine sediment to the bottom of the sea. And that can actually generate electricity already from the sediment at the bottom of the sea. And so scientists are looking to see how they can actually provide an electricity source for things like sensing apparatus that would measure temperature and current and so on, and beam that data back up to the surface for, you know, ocean scientists to collect.

FLATOW: There's an old song in America. "There's a hole..."

BURGESS: (Unintelligible) applications are not far way at all.

FLATOW: "There's a Hole in the Bottom of the Sea." And now, we know what goes into that, a little marine sensing device. And you have been studying marine bacteria for decades, right? And you think that's a really fertile place to find interesting, new creatures.

BURGESS: It is. I mean, as you said, I mean, I've been studying about marine bacteria now for about 25 years or so. And, you know, they never seize to amaze me. I think there are some really amazing examples of bacteria out there. And I suppose one thing that fascinates me is how complicated they are. You know, we found a few years go that bacteria actually have a sense of smell.

FLATOW: Really?

BURGESS: So that, you know, they can actually detect each other by monitoring molecules that are in the air. And we found that bacteria actually detect each other by monitoring ammonia, and they change their behavior as a result. So we were amazed by that, and it just shows you the complexity of the ways in which bacteria can communicate with each other.

FLATOW: Mm-hmm. And you study something called snot worms, correct?

BURGESS: Well, that's - they are incredible. Yeah. I mean, to give it a full name, it's actually a bone-eating snot worm. And these are very, very unusual marine creatures that live at the depths of the sea. And - I mean, if you ever thought about what happens when something large like a whale dies - so, you know, a whale, when it dies, will sink to the bottom of the ocean and there will be a whole load of fat and oil for marine creatures to eat. And, you know, once the meat and the blubber, if you like, have all been eaten by other creatures, you're left with huge whale bones.

And along come these snot worms. And what they do is they actually colonize the bones, and they are effectively a worm with a whole big root structure, which burrows into the bone and actually dissolves the bone and extracts nutrients from the bone and takes these nutrients up inside the worm as a food source. And one of the most bizarre things about snot worms is that they have no mouth and no anus, and so they actually absorb these nutrients directly through these root structures.

And if you look a little bit further at the root structure, you find that the root structures are actually packed full of symbiotic bacteria that exude enzymes and so on, to be able to break down these fats and oils and in fact the bone itself and pass the nutrients back to the worm. You know, it's almost like a science-fiction story, but this is real.

FLATOW: Well, you've given us something to think about today, Dr. Burgess. Thank you very much. Fascinating.

BURGESS: Thank you.

FLATOW: And good luck with your work with the bacteria. Grant Burgess is professor of marine biotechnology at Newcastle University in the U.K., author of a study, Environmental Science & Technology. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

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