This SciShow video is supported by Revisionist History, bestselling author Malcolm Gladwell's
podcast which journeys through the overlooked and misunderstood.
Click the link in the description to binge the entire season now on Malcolm Gladwell’s
YouTube channel or search for Revisionist History wherever you get your podcasts.
[♪ INTRO]
The name “E. coli” is enough to strike terror into the hearts, or stomachs,
of anyone who’s experienced food poisoning.
But, hear me out: E. coli isn’t all bad.
Just a few varieties have given this whole species of bacteria a bad reputation.
When you start looking at what the other varieties can do, it turns out,
E. coli can do some pretty incredible things, from fighting climate change to fighting disease.
E. coli is short for Escherichia coli.
And as a species, it’s sturdy and adaptable.
These bacteria aren’t picky about what they eat, or even whether there’s oxygen around.
One bacterium can also double itself every 20 minutes,
which is why just a few pieces of that contaminated lettuce sent you to the bathroom so fast.
But not all kinds of E. coli make you puke.
One strain, called E. coli O157:H7, is the villain here:
It makes a toxin that causes food poisoning.
But there are detailed records about more than 85,000 strains of E. coli.
And tens of thousands of them don’t make that toxin.
Also, not only will they not give you diarrhea,
but some of these other varieties differ in ways that make them useful tools for bioengineers.
Most notably, E. coli can pick up new bits of DNA from its surroundings,
and use that DNA pretty much right away.
That’s because, unlike animals like us, bacteria don’t keep DNA packaged away in a nucleus.
All of their DNA-reading equipment is freely floating around in their single-celled selves.
So, if a new bit of DNA shows up, great!
It’ll quickly get read like anything else.
There’s no special step where they have to go rummaging around
in the nucleus for that information first.
And scientists have put this to use in the lab.
With genetic engineering, researchers can take E. coli
from an occasional supervillain to a microscopic hero.
For example, some experts have proposed using E. coli to reduce our reliance on fossil fuels.
Many fossil fuels are refined from crude oil, which is what’s left behind
after organisms die and go through millions of years of geologic processing.
These fuels pack a lot of energy into a relatively small space,
which is part of why we’ve been relying on them for hundreds of years to power our machines.
But burning them also releases pollutants that affect human health,
plus greenhouse gases that are driving up the temperature on our planet.
So, now, engineers are working to develop all kinds of alternative energy sources
and technologies to help us move away from fossil fuels.
And one of them involves E. coli!
Bioengineers are finding ways to use this bacterium to turn sugar and fat
into the same energy-dense molecules found in fossil fuels.
For instance, the truck that dropped off your packages this morning likely ran on diesel.
And diesel is a mixture of long hydrocarbons,
which are molecules made of hydrogen and carbon.
They come in a variety of shapes, like long chains, branches, or rings.
In one study, researchers showed that they could engineer E. coli to take sugar
that they would normally use for other things, and turn it into hydrocarbons
with the same length and branched shape as some molecules in diesel.
In another study, other scientists created a pair of engineered E. coli strains.
And together, they could turn sugar into olefins, another type of hydrocarbon found in diesel.
To pull this off, both of these studies used pretty similar strategies.
First, the researchers found examples of other organisms that could take fatty acids
or sugars and make specific changes to their chemical structures.
Then, they figured out which genes caused those chemical reactions
essentially, what instructions these organisms were using to make those reactions happen.
And finally, they put those instructions into E. coli,
turning the bacterium into a microscopic factory.
Basically, the raw materials, like sugar and fatty acids, go in, and then the new genes tell the
bacterial cells how to turn those molecules into diesel-sized and diesel-shaped hydrocarbons.
Now, at this point, nobody has actually used E. coli to make fuel to power a car,
or any other vehicle.
At least, not yet.
But fossil fuels are so embedded in our world
that we’re going to need some creative solutions to move away from them.
So, even early research like this puts us one step closer to a healthier future for the planet.
Speaking of a healthier future, E. coli might also be able to clean up
another kind of pollution: antibiotics.
If that’s a weird sentence, we hear you.
This relationship usually goes in the other order:
People are normally using antibiotics to fight E. coli, but not the other way around.
But this doesn’t always go as planned.
Some bacteria have evolved to defend themselves from our medicines.
In some cases, they break down the chemicals in antibiotics themselves.
And for the most part, this is a big problem!
Bacteria are becoming resistant to the medicines we use to fend them off,
and that makes it harder for us to keep people and animals healthy.
But even this has a silver lining.
If bacteria are breaking down antibiotics…
well, we might as well put them to work in situations where we want that to happen.
We use a lot of antibiotics in medicine and agriculture,
so they can get out into the environment and pollute soil and waterways.
And there, they can mess with wild bacteria.
Some of these bacteria might die, while others might develop antibiotic resistance.
And that in particular could come back to haunt us, because if these resistant bacteria
started causing infections, we’d have fewer tools to fight them with.
So, some researchers are using E. coli
to try and clean up the environment before that happens.
For instance, in a 2018 paper, researchers in China engineered E. coli
to break down tetracyclines, a common antibiotic, into smaller, less damaging pieces.
They did it by using a gene from another bacterium
that can’t survive when there’s a lot oxygen around.
And in other work, researchers in the United States have shown that,
with a couple of new genes, E. coli can also survive
on a diet of penicillin, another antibiotic, and its byproducts.
This sounds like a great solution!
But there’s a catch: These bacteria aren’t actually very fast eaters.
And in places like sewage plants where we really need to clean up antibiotics,
there’s so much pollution that E. coli would take too long to be effective.
So now, researchers want to turn these E. coli into competitive eating champions,
and modify them to break down the antibiotics faster.
Then, they can start making plans to deploy them as a soil clean-up squad.
For both biofuels research and pollution clean-up,
scientists rely on domesticated versions of E. coli.
These strains can’t do tricks like your dog, but they have been specifically studied
for lab work, and they’re really consistent in how they behave.
That’s amazing for researchers growing bacteria in lab dishes!
But these bacteria have been modified enough that they aren’t so great at living in animal guts.
So, for scientists who want to study the community of microbes living in and on you,
wild type E. coli are more useful.
Broadly speaking, they’re any kind of E. coli that naturally lives in the environment.
And that brings us to one, final example of how these bacteria can be turned into superheroes.
Research published in August 2022 proposed a way to engineer wild type E. coli to treat
Type 2 diabetes.
Like in many cases, the scientists tested their idea on mice.
They gathered stool samples from the animals, and isolated some E. coli from the poop.
Our condolences to whatever lab tech got that job,
but it was at least easier than what came next.
Ultimately, the researchers modified this E. coli and made two versions of it:
one with a bacterial gene called bile salt hydrolase,
and another with a mammalian gene called IL-10.
Bile salt hydrolase affects the production of bile acids,
which play a role in how animals digest sugar.
And IL-10 is usually found in mammals,
and it reduces inflammation.
Since Type 2 diabetes involves problems regulating sugar and inflammation,
the idea was that these genes would help with symptoms.
So, the team eventually put both kinds of E. coli into mice
who’d been engineered to be little, mousey models for this disease.
Amazingly, the modified bacteria settled right into their guts.
They unpacked, put their little E. coli feet up, and made themselves at home.
And even better?
They worked!
Thanks to the genes in the modified E. coli,
the mice with these bacteria had fewer symptoms of diabetes for the rest of their lives.
Now, this strategy hasn’t been tested in humans yet.
There’s a big leap between knowing something works in mice
and knowing something is safe to try on us.
But the researchers have taken the first step in that direction
by proving that wild-type E. coli from the human gut
can at least be genetically engineered in general.
And maybe someday, E. coli could be used to treat diseases like diabetes.
Overall, researchers are using E. coli to fight some of humanity’s biggest challenges,
from disease, to fossil fuels, to pollution.
And that’s just the tip of the iceberg.
Genetic engineers rely on E. coli to do groundbreaking research in labs around the world.
So next time E. coli makes headlines for a food recall, remember:
That’s just one pesky old strain.
Lots of E. coli are hard at work making the world a better place.
Thank you for watching this SciShow video and thanks to Revisionist History for supporting it!
Every SciShow video walks you through discoveries from experiments that researchers
have conducted around the world, because the world is knowable.
Likewise, the podcast, Revisionist History, digs into what experiments can teach us,
why we need more of them, and why we so often learn the wrong lessons about them.
The host, Malcolm Gladwell, is obsessed with experiments,
because the list of things we don’t know is longer than the things we do know.
In this season, he’ll examine natural experiments, thought experiments, failed experiments,
and experiments that would never fly today.
The podcast goes everywhere from salt factories, to university campuses,
to the Library of Congress, and even to the set of the original A Star is Born movie.
To binge the entire season now on Malcolm Gladwell’s YouTube channel, you can click the link
in the description down below or search for Revisionist History wherever you get podcasts.
[♪ OUTRO]