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How These Bacteria Become Electrical Cables That Could Power Our World

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It turns out that bacteria may have figured
out the whole electricity thing way before we did, you guys. In fact, there are bacteria deep in the ground
and under the ocean right now that are acting as living electric cables, and scientists
are coming up with all sorts of cool new ways to study them…and maybe even use them. Electron-transporting bacteria were a mystery
up until a couple decades ago and what makes them unique is that some of them may not need
anything but electrons to survive. See, every living thing needs a source of electrons
to survive, but the difference is that we can’t just lick an electrode for all the
energy we need. Both Shewanella and Geobacter species, for
example, breathe rock. When no oxygen is available, these species
use their pili, or little electrically conductive ‘nanohairs’ to transport electrons
to nearby rocks, putting their electrons into metals like iron in the same way we put our body’s
electrons into oxygen. One team at the University of Southern California
is now attempting to grow bacteria directly on an electrode without giving it anything
else, just to see if they can survive on pure electrons. Delving into this whole world of electric
bacteria has made scientists think, ‘Hey! What else out there is like this.’ And in recent years they observed something
very strange. Electric currents were detected in the seafloor,
but we didn’t know what the source was. And when we took a closer look? Surprise, bacteria! But these work a little differently: they’re
called “cable bacteria”, and they’re remarkable, maybe one of the most striking
discoveries of the last few decades in microbiology. They also live in areas with little to no
oxygen, like far down in the sediments at the bottom of a body of water. They can connect deep layers of the soil—where
there is no oxygen to breathe—with surface layers, where oxygen is present. And how they do it is maybe the most remarkable
piece of all. Cable bacteria are actually multicellular
microorganisms—which is pretty rare in the bacterial world. And what you’re looking at right now is not little nanohairs grown by the bacteria, as is the case with other electrically conductive
microbes…these structures are the bacteria themselves. They are the cable! They can span up to a few centimeters, which
is a huge distance for a microorganism like a bacterium, shuttling electrons like a little
snorkel. That’s how they carry out their respiration
process, which is what generates their energy and which also generates an electric current. These
electrically conductive ‘cables’ can even connect to each other, forming extremely dense
networks of what is essentially living electricity. Which you can imagine, opens up a whole world of possibilities. Researchers across the world believe they’ve
identified at least six new species of cable-connected bacteria that live in places like tidal pools,
mud flats, and salt marshes. And a new study that measured the properties
of this kind of bacteria for the first time showed that these biocables can sustain an electric that’s current comparable to the current density in copper wiring that we use in our everyday
lives! Think about it—this could give us electricity
that you can grow. I mean, some scientists think that these bacterial
mats could be forming networks that extend for hundreds of meters—and we didn’t
even know about these bacterial biocables until recently. So imagine what else we’ll uncover about them
as we continue to explore! But there are lots of other big implications
too. Scientists think that these interconnected
mats of complex microorganisms could be involved in the regulation of Earth’s soil and
ocean biogeochemistry, which is something we’d never considered before. Other non-cable electric bacteria could be
incorporated into machines called self-powered useful devices. These SPUDs could be sent into places that
have some kind of chemical that needs to be cleaned up, full of microorganisms that could
be genetically engineered to adhere to or absorb that pollutant, while also creating
the electricity needed to power the machine just by cycling electrons from their surroundings. Bacteria that exhibit these electric properties
often live in extreme places where there’s not a lot else to breathe—that’s what
drives ‘em to the electric life, so to speak. This is important because it provides a model
for life in other places with no other things for living stuff to eat…like, I dunno, other planets? So bacteria like Geobacter species, that can
survive basically just with access to metal, could give us helpful clues about what kinds
of organisms could be living out there in the rest of the universe. These organisms give us important insight
into what the bare minimum required for life really is, letting us guess not only about
life out in space, but about the origin of life here on Earth too. Tiny but mighty, and changing the world, one
electron-conducting bacterial appendage at a time. Gotta love ‘em! If you want more on the amazing things that
bacteria can do, check out this video here, and let us know down in the comments what
crazy bacterial species you want to learn about next. Make sure you subscribe to Seeker to stay
up to date with all your microbial news and as always, thanks for watching.

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