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  • From: Lawrence London <lfljvenaura@gmail.com>
  • To: permaculture <permaculture@lists.ibiblio.org>, sustagnet@googlegroups.com
  • Subject: [permaculture] Meet the electric life forms that live on pure energy | New Scientist
  • Date: Thu, 16 Jan 2020 04:14:16 -0500

Meet the electric life forms that live on pure energy | New Scientist
https://www.newscientist.com/article/dn25894-meet-the-electric-life-forms-that-live-on-pure-energy/?fbclid=IwAR2diYXCakQbYJrBg86wSARwKr9tk8Y1rHoE5eTq5IunZtUz2ap_zRfH4lA#.XV__mmRk6Mc.facebook

Meet the electric life forms that live on pure energy

Unlike any other life on Earth, these extraordinary bacteria use energy in
its purest form – they eat and breathe electrons – and they are everywhere
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Life <https://www.newscientist.com/subject/life/> 16 July 2014

By Catherine Brahic <https://www.newscientist.com/author/catherine-brahic/>
[image: New Scientist Default Image]
Geobacter – a current favourite

Derek Lovley/SPL

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*
<https://www.newscientist.com/article/mg20827915-800-live-wires-the-electric-superorganism-under-your-feet>.
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, says Kenneth Nealson
<http://dornsife.usc.edu/cf/faculty-and-staff/faculty.cfm?pid=1003571> 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.

“Life’s clever. It figures out how to suck electrons out of everything we
eat and keep them under control”

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.

“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.”

Video: Electric bacteria connect to form wires

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.

“Basically, the idea is to take sediment, stick electrodes inside and then
ask ‘OK, who likes this?’,” says Nealson.
Shocking breath

At the Goldschmidt geoscience conference in Sacramento, California, last
month, Shiue-lin Li of Nealson’s lab
<http://dornsife.usc.edu/labs/nealsonlab/members/> 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 <http://mbio.asm.org/content/4/1/e00420-12>). That research,
says Jangir’s supervisor Moh El-Naggar
<http://dornsife.usc.edu/cf/faculty-and-staff/faculty.cfm?pid=1013055>, 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 like *Shewanella* 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.”

“This is huge. What it means is 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
<https://www.newscientist.com/article/mg22229742-500-weird-organisms-emerge-from-the-deep-dark-biosphere>
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
<http://faculty.rpi.edu/node/1179>, 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.

*Leader:* “Spark of life revisited thanks to electric bacteria
<https://www.newscientist.com/article/mg22329781-600-spark-of-life-revisited-thanks-to-electric-bacteria>

Wire in the mud

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
<https://www.newscientist.com/article/mg21428712-300-giant-living-power-cables-let-bacteria-respire>.
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 (see video).
Flexible biocables

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.

*This article appeared in print under the headline “The electricity eaters”*

Read more:
https://www.newscientist.com/article/dn25894-meet-the-electric-life-forms-that-live-on-pure-energy/#ixzz6BBQ1CwLI



  • [permaculture] Meet the electric life forms that live on pure energy | New Scientist, Lawrence London, 01/16/2020

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