By   Catherine Brahic,  New Scientist September 2014 

 

http://www.newscientist.com/article/dn25894-meet-the-electric-life-forms-that-live-on-pure-energy.html     

 

Unlike any other life on Earth, these extraordinary bacteria use energy in its purest form - they eat and breathe electrons - and they are everywhere.

STICK an electrode in the ground, pump electrons down it, and they will come: living cells that eat electricity. We have known bacteria to survive on a variety of energy sources, but none as weird as this. Think of Frankenstein's monster, brought to life by galvanic energy, except these "electric bacteria" are very real and are popping up all over the place.

 

Unlike any other living thing on Earth, electric bacteria use energy in its purest form - naked electricity in the shape of electrons harvested from rocks and metals. We already knew about two types,Shewanella and Geobacter. Now, biologists are showing that they can entice many more out of rocks and marine mud by tempting them with a bit of electrical juice. Experiments growing bacteria on battery electrodes demonstrate that these novel, mind-boggling forms of life are essentially eating and excreting electricity.

 

That should not come as a complete surprise, saysKenneth Nealson at the University of Southern California, Los Angeles. We know that life, when you boil it right down, is a flow of electrons: "You eat sugars that have excess electrons, and you breathe in oxygen that willingly takes them." Our cells break down the sugars, and the electrons flow through them in a complex set of chemical reactions until they are passed on to electron-hungry oxygen.

 

In the process, cells make ATP, a molecule that acts as an energy storage unit for almost all living things. Moving electrons around is a key part of making ATP. "Life's very clever," says Nealson. "It figures out how to suck electrons out of everything we eat and keep them under control." In most living things, the body packages the electrons up into molecules that can safely carry them through the cells until they are dumped on to oxygen.

Electric bacteria connect to form wires

 

"That's the way we make all our energy and it's the same for every organism on this planet," says Nealson. "Electrons must flow in order for energy to be gained. This is why when someone suffocates another person they are dead within minutes. You have stopped the supply of oxygen, so the electrons can no longer flow."

 

The discovery of electric bacteria shows that some very basic forms of life can do away with sugary middlemen and handle the energy in its purest form - electrons, harvested from the surface of minerals. "It is truly foreign, you know," says Nealson. "In a sense, alien."

 

Nealson's team is one of a handful that is now growing these bacteria directly on electrodes, keeping them alive with electricity and nothing else - neither sugars nor any other kind of nutrient. The highly dangerous equivalent in humans, he says, would be for us to power up by shoving our fingers in a DC electrical socket.

 

To grow these bacteria, the team collects sediment from the seabed, brings it back to the lab, and inserts electrodes into it.

 

First they measure the natural voltage across the sediment, before applying a slightly different one. A slightly higher voltage offers an excess of electrons; a slightly lower voltage means the electrode will readily accept electrons from anything willing to pass them off. Bugs in the sediments can either "eat" electrons from the higher voltage, or "breathe" electrons on to the lower-voltage electrode, generating a current. That current is picked up by the researchers as a signal of the type of life they have captured.

 

At the Goldschmidt geoscience conference in Sacramento, California, last month, Shiue-lin Li of Nealson's lab presented results of experiments growing electricity breathers in sediment collected from Santa Catalina harbour in California. Yamini Jangir, also from the University of Southern California, presented separate experiments which grew electricity breathers collected from a well in Death Valley in the Mojave Desert in California.

 

Over at the University of Minnesota in St Paul, Daniel Bond and his colleagues have published experiments showing that they could grow a type of bacteria that harvested electrons from an iron electrode (mBio, doi.org/tqg). That research, says Jangir's supervisor Moh El-Naggar, may be the most convincing example we have so far of electricity eaters grown on a supply of electrons with no added food.

 

But Nealson says there is much more to come. His PhD student Annette Rowe has identified up to eight different kinds of bacteria that consume electricity. Those results are being submitted for publication.

 

Nealson is particularly excited that Rowe has found so many types of electric bacteria, all very different to one another, and none of them anything likeShewanella or Geobacter. "This is huge. What it means is that there's a whole part of the microbial world that we don't know about."

 

Discovering this hidden biosphere is precisely why Jangir and El-Naggar want to cultivate electric bacteria. "We're using electrodes to mimic their interactions," says El-Naggar. "Culturing the 'unculturables', if you will." The researchers plan to install a battery inside a gold mine in South Dakota to see what they can find living down there.

  

NASA is also interested in things that live deep underground because such organisms often survive on very little energy and they may suggest modes of life in other parts of the solar system.

 

Electric bacteria could have practical uses here on Earth, however, such as creating biomachines that do useful things like clean up sewage or contaminated groundwater while drawing their own power from their surroundings. Nealson calls them self-powered useful devices, or SPUDs.

 

Practicality aside, another exciting prospect is to use electric bacteria to probe fundamental questions about life, such as what is the bare minimum of energy needed to maintain life.

For that we need the next stage of experiments, says Yuri Gorby, a microbiologist at the Rensselaer Polytechnic Institute in Troy, New York: bacteria should be grown not on a single electrode but between two. These bacteria would effectively eat electrons from one electrode, use them as a source of energy, and discard them on to the other electrode.

 

Gorby believes bacterial cells that both eat and breathe electrons will soon be discovered. "An electric bacterium grown between two electrodes could maintain itself virtually forever," says Gorby. "If nothing is going to eat it or destroy it then, theoretically, we should be able to maintain that organism indefinitely."

 

It may also be possible to vary the voltage applied to the electrodes, putting the energetic squeeze on cells to the point at which they are just doing the absolute minimum to stay alive. In this state, the cells may not be able to reproduce or grow, but they would still be able to run repairs on cell machinery. "For them, the work that energy does would be maintaining life - maintaining viability," says Gorby.

 

How much juice do you need to keep a living electric bacterium going? Answer that question, and you've answered one of the most fundamental existential questions there is.

 

Electric bacteria come in all shapes and sizes. A few years ago, biologists discovered that some produce hair-like filaments that act as wires, ferrying electrons back and forth between the cells and their wider environment. They dubbed them microbial nanowires.

Lars Peter Nielsen and his colleagues at Aarhus University in Denmark have found that tens of thousands of electric bacteria can join together to form daisy chains that carry electrons over several centimetres - a huge distance for a bacterium only 3 or 4 micrometres long. It means that bacteria living in, say, seabed mud where no oxygen penetrates, can access oxygen dissolved in the seawater simply by holding hands with their friends.

 

Such bacteria are showing up everywhere we look, says Nielsen. One way to find out if you're in the presence of these electron munchers is to put clumps of dirt in a shallow dish full of water, and gently swirl it. The dirt should fall apart. If it doesn't, it's likely that cables made of bacteria are holding it together.

 

Nielsen can spot the glimmer of the cables when he pulls soil apart and holds it up to sunlight 

 

It's more than just a bit of fun. Early work shows that such cables conduct electricity about as well as the wires that connect your toaster to the mains. That could open up interesting research avenues involving flexible, lab-grown biocables.

 

RELATED ARTICLES 

 

Spark of life revisited thanks to electric bacteria The discovery and culturing of bacteria that eat and excrete electrons means we may soon find out just how little electricity fundamental life requires

Power plants: Grow your own electricity Imagine charging your cellphone from a meadow or harvesting electricity from rice paddies. The technology works, but can we make plant power a staple crop?

Modified bacteria could get electricity from sewage Using genetically engineered bacteria to capture energy stored in waste water could make treatment cheap and energy-efficient

 

 

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by Leonard David, SPACE.com's Space Insider Columnist   |   September 22, 2014 

http://www.space.com/27225-space-elevator-technology.html?cmpid=558275

 

 

SEATTLE - Sure, it's a stretch. Envision a thin, vertical tether extending from the Earth's surface to a mass far out in space. Scooting up the tether are electric vehicles, climbers that are energized by a combination of sunlight and laser light projected from the ground.

 

Here's the kicker: Carrying payloads and people, the climbers travel at speeds comparable to those of a fast train - taking several days of transit time - but are launched once per day. These space elevators have the potential to be a revolutionary way to access space less expensively than possible with chemical rocket technology. And innovators today are working to make that happen.

 

Last month, the International Space Elevator Consortium (ISEC) held its annual meeting here at the Museum of Flight in Seattle, with a theme focused on space elevator architectures and road maps. The meeting featured mini-workshops on global cooperation and marine node designs to anchor the elevator on Earth. [Is a Space Elevator to the Moon Possible? (Video)]

 

The space elevator discussions, which ran from Aug. 22 to 24, could be described as a kind of "heightened awareness," as scientists,engineers, entrepreneurs, infrastructure experts and others brainstormed climber designs, new materials, technology trends,business strategies, operations and legal issues.

 

Among the space-elevator devotees taking part were officials from the Japan Space Elevator Association, which spotlighted a number of climber approaches, promoting the idea of a climber competition as a worldwide event.

 

For good measure, toss in a sort of space "elevator pitch" competition. That is, selling the idea to an influential person - say, Microsoft co-founder Bill Gates - in 90 seconds. How best to ask for their buy-in of the concept - without being tossed into the elevator shaft!

 

"The conference was a rewarding experience ... good ideas, new concepts and great participation," said Peter Swan, president of the International Space Elevator Consortium.

"The ISEC was developed to specifically broaden the knowledge about space elevators and incrementally reduce the risk for its development," Swan said. "We're trying to address the unknown unknowns that are out there."

 

Skip Penny, ISEC director, said the space-elevator gathering was an opportunity to "have a spark create another spark." The space elevator is a huge systems-engineering job, he added.

"We're so far away from bending metal," Penny told Space.com. "We're advancing, but there's need for money. It is two steps. One is seed money so we can refine our ideas and understandings, then build product."

 

So what's next on the ISEC agenda? 

 

"The next steps for the development of space-elevator infrastructures are focused around the creation and funding of a Space Elevator Institute," Swan said. The institute would fund research projects addressing critical issues. 

 

The development of prototype experiments, including tether material design for tensile strength, would be funded by the Space Elevator Institute, he added.

 

Currently, the "magic" material that's boosted the promise of a space elevator is the carbon nanotube. But moving from vials of the stuff to miles and miles of space-worthy tether is no easy task.

 

Similarly, graphene is also being eyed as a potential material for the space elevator. Graphene is pure carbon, remarkably strong for its very low weight and far stronger than steel.

 

Revolutionizing high-strength materials for a better world is the quest of Bryan Laubscher, president of Olympia, Washington-based Odysseus Technologies.

 

"You have to work on materials," Laubscher told Space.com "Making carbon nanotubes through chemical vapor deposition is so inferior to what we could get."

Laubscher is working to grow carbon nanotubes in a new way, with experiments on his near-term to-do list.

 

"Carbon nanotubes and graphene could be the way forward ... pervading society and gaining accelerated acceptance by society ... like the industrial revolution did in creating cheap steel," he said.

 

"When the carbon nanotube or alternative material develops to the point where we can actually build a space-elevator tether, we want to be at a mature design phase," Swan said. "Then, we can go right into the development, planning and execution of a space-elevator infrastructure." 

 

Admittedly, the tether material is a major hurdle, Swan said.

"Taking that material and grow[ing] it 1 meter (3 feet) wide and over 62,000 miles (100,000 kilometers) long - neither of those is a trivial activity."

 

Swan said the material challenge is not being driven by the space industry. Rather, automobile makers, airlines and even the ski-lift industry are looking for stronger materials.

"The beauty of the situation," he said, "is that the global need for the material is driving it - and we just need to tag along."

 

For more information on the International Space Elevator Consortium, visithttp://www.isec.org.

 

 

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