This episode is supported by Wren, a website  with a monthly subscription that helps fund   projects to combat the climate crisis.

Click the  link in the description to learn more about how   you can make a monthly contribution to support  projects like rainforest protection programs. [♪ INTRO] Since almost the beginning  of commercial oil production,   engineers have had a problem with  things living in the oil reservoirs. Not around the reservoirs.  We’re talking microorganisms   living inside the blob of oil  hundreds of meters below the surface.

Until recently, it was thought  these critters had just caught   a ride down there from the surface on  some drilling equipment. But it appears   that some have actually been  down there for a long, long time. And through a combination of home  renovation and a special kind of   digestion, these tiny critters can  show us just how hearty life can be.

Now, when I say “oil reservoir,” some people  might have a picture that pops in their mind   of like the pumpjack or oil rig, but that’s  just the machinery sitting above the reservoir. The oil reservoir itself is underground,   and formed out of a pocket or  series of gaps in the rock. Sometimes these can be  pretty close to the surface,   but many are deep underground…as  far as five and a half kilometers.

In addition to oil, the reservoir  has a fair amount of water, either as   a separate layer below the oil, or mixed up with  the oil in the form of isolated tiny bubbles,   since oil and water can’t mix fully. And it’s on these borders between oil  and the water where microbes can live.   We’re talking bacteria as well as another  group of organisms called archaea. Now, some species definitely arrived after  humans breached the ecosystem.

Because to free   up the oil, drilling crews sometimes have  to pump water or gas down into the wells,   and outside microbes can get  swept along for those rides. But other microbes were likely  there before humans even existed. Oil deposits get their start when dead  organisms like algae settle at the bottom   of a body of water, and then get buried  under layers upon layers of sediment.

Over millions of years, the molecules in  their dead bodies break down and turn into   oil or gas. ~ But if some organisms were buried  alive, their descendants could have survived   in those reservoirs anywhere from the 10 to 180  million years it took for humans to dig them up. This hypothesis might seem a little  far-fetched, but scientists have also   discovered microbes living over two  kilometers beneath the ocean floor. On the other hand, species could also  have arrived before humans discovered   the oil reservoir, if sea water or fresh  water from an aquifer somehow got inside.

Scientists are still working to figure  out the origin story of these critters.   And they’re also working on how  they manage to survive their toxic,   acidic, high pressure, and pitch black  home…which also has very little water. And thanks to minerals leaching from the rocks,   what water they do have access to is  three to six times saltier than sea water. And being that far below ground, it’s  also hot.

Deep oil reservoirs can reach   temperatures above 150 degrees Celsius.  Even the most heat-loving microbes,   like the ones that live in Yellowstone’s  geysers, tend to die when it hits 120 degrees. But some, if not most of these  microbes have figured out a special   way to survive the harsh conditions around them. Instead of just freely  floating around willy nilly,   they’ve actually built their  own protective form of housing.

They’re called biofilms…mat-like   structures that microbial colonies create  by excreting proteins and other compounds. It’s basically like if you and your family could  just build your own house out of your snot. These biofilms protect microbes from their  environment by keeping excess salt away,   or by forming a kind of heat-shield.

They  can even create community homes, where   multiple species help each other survive. And they can also break the oil glob into  smaller bits…so that the microbes can eat. Many of these species produce the  energy their single-celled bodies   need by breaking down the hydrocarbon molecules   in oil…those are the ones made up primarily of  carbon and hydrogen, like propane or octane.

Meanwhile, other species get their  energy by performing chemical reactions   with smaller compounds like sulfates or nitrates. Sulfate, for instance, is a chemical consisting  of one sulfur atom and four oxygens. So while   human cells get their energy by converting  sugar molecules into carbon dioxide and water,   these little critters change sulfate  into compounds like hydrogen sulfide.

In fact, some microbes eat so much  that oil engineers often have to   account for their digestion when  setting up a drilling operation. For instance, they might monitor how much  sulfate is in the water they inject into the   reservoir. Because if those sulfate-eating  microbes make too much hydrogen sulfide,   it can corrode the oil rig’s steel  and even poison human workers.

Or alternatively, they might have a more direct   hand in what microbe populations  are allowed to live down there. They can “disinfect” the  reservoir with certain chemicals,   or even stimulate microbe growth by pumping in  extra nutrients. That’s because, in some cases,   the chemicals the microbes give off can actually  help the oil flow up to the surface more easily.

So depending on the species  that’s already in a given well,   engineers might purposefully introduce  new microbes to increase oil production! As for how much humans are messing up these  microbial homes, there hasn’t been a lot of   research. But there are hints that our meddling  can influence which species thrive over time.

For example, one analysis of the  Halfdan oil field off the coast of   Denmark found that after people started  drilling there, slow-growing oxygen-shy   species that had once been dominant were  pushed out by oxygen-loving hotshots. Studying these little guys is really fascinating,  both because of their incredible backstory,   and because it’s yet another example of an  ecosystem affected by humans using fossil fuels. But it also makes us think a little.  Oil drilling can seem so artificial,   such a modern human invention.

So when life  shows up, we assume it’s interrupting us. But no. It is actually us who’s interrupting them.

Thanks for watching this SciShow video and  thank you to Wren for supporting it! Wren is a website that helps fund  projects that combat the climate crisis,   like protecting the Amazon rainforest. Wren is currently raising  funds to protect biodiversity,   prevent deforestation, and  promote Indigenous land rights.

And, of course, that  biodiversity includes microbes. Using satellite and drone monitoring technology, Indigenous Amazonians in the Ticuna  community of Buen Jardín de Callaru in Peru can detect deforestation early and protect  their rainforest before it disappears. This project provides the technology  to combat illegal logging.

That means saving the trees that  absorb about 350 million metric tons of atmospheric carbon dioxide every year. Once you sign up to make a monthly  contribution to projects like this one,   you’ll receive monthly updates on their progress. You’ll get to see the good you’re doing  and what your money is being spent on.

You can start helping today by learning more  at wren.co. But you will not be alone in this   effort. We’ve partnered with Wren to plant  10 additional trees for the first 100 people   who sign up using the referral  link in the description down below! [♪ OUTRO]