Thanks to Babbel, a language learning app, for sponsoring this episode.

If you’re interested in growing your language skills, Microcosmos viewers get up to 60% off with a 20 day money-back guarantee when you sign up using our link in the description. Our world today, the one that we have constructed, feels as if it runs on plastic.

It is a building block in our bags, our bottles, clothing, toys… the list it go on and on. Plastic has become so prevalent that it is, for all intents and purposes, impossible to escape. Even in the microcosmos, plastic is inevitable.

It persists in long, still threads that could have come from anything. Maybe it was shed from a piece of clothing, or it came off a car part. Whatever it once was, this shred of microplastic is one of many pieces just like it turning the microcosmos into a burial ground for our waste.

But microbes are crafty, they're capable of making lives out of the most unusual ingredients— including plastic. So what does that look like, for them and also for us? Well, first let’s be human about it and focus on ourselves for a bit, and particularly our love for plastics.

We currently make around 400 million tons of plastic every year, but why? Well “plastics” covers a wide range of materials. At a chemical level, they are made of structures that repeat over and over, creating a pattern that builds into a material that is moldable under the right temperatures and pressures.

And nature is full of materials like this that would end up driving our love of plastics, including natural rubber and plant cellulose, even wood is a chemical polymer. But nature sets some constraints on how much we can take, and precisely what's available. And at the turn of the 20th century, the advances of chemistry and the demands of war meant that synthetic plastic was primed to take over— first as part of military vehicles and parachutes and other wartime needs, and then after in consumer goods like Tupperware.

They were cheaper and lighter than glass and metal, and so versatile. But while we’ve lived with the benefits of these synthetic plastics for more than a century now, we’re also living with their harms. Plastics don’t just surround us in the objects we make, they last in these invisible forms, smaller than 5 millimeters in length.

Some might come off our clothes when we wash them, others might be part of our cosmetics. They can loft into the air and come back down with rain, or they can travel through our waterways, ending up in ponds and oceans. James, our master of microscopes, found most of the samples we’re looking at today floating in his plankton net while gathering microbe samples.

And on their own, these small fragments of plastic seem so inconsequential. But in a world like ours, where everything is connected, nothing is inconsequential. Microplastics get eaten by animals, they break down into chemicals that can be toxic and those get leached into the environment.

But the consequences do not stop there. Animals get eaten by other animals, which then get eaten by other animals, and so on. And with each step up and around the food web, microplastics and their toxins accumulate.

Scientists are still working to understand how microplastics affect our ecosystems and our bodies. But one of the challenges with microplastics is just how durable they are. Those long chains of atoms, once assembled, tend to stay that way.

One way to curb the amount of microplastics that end up in our world and in us is to stop making as much new plastic and instead, you know, recycle what we’ve already made. Unfortunately, only a small fraction of the massive amount of plastic we produce each year gets recycled. Some of the challenges are in our infrastructure, like figuring out how to sort different types of plastics so they can be properly recycled without mixing them up with each other.

Some of it is technological, in finding ways to break down the most challenging plastics, or developing tools to ensure recycled plastic is just as good as the original. And that has led scientists to turn to the microcosmos for possible answers, with one particular question in mind: can microbes eat plastic? Now there are many ways to investigate that question, and for Maria Pinto— a scientist who has sent us samples before— it’s taken her out onto the ocean as she looks to see how bacteria gather on plastics.

The samples come from all over. Some are from the Atlantic Ocean, some from the Pacific Ocean, some from the Adriatic Sea. The ubiquity of microplastics in her samples feels similar to the way we find microbes everywhere, but without the wonder and awe that microbes inspire.

Now microbes are everywhere because they find a way to endure, adapt, and spread. Their ubiquity is a marker of their ingenuity. Microplastics, on the other hand, are a product of our ingenuity, but also of our carelessness with our creations.

It also fits that these two pervasive entities would find each other. Maria has seen the bacteria gathering on microplastics, their cellular bodies producing enzymes that might even be able to break down the plastics into their individual units for the bacteria to use. Scientists are looking in plenty of other places too.

Greek beaches. Mud near a Japanese plastic recycling factory. Hot springs in Yellowstone National Park.

These diverse iterations of the microcosmos and the plastic-eating bacteria in them teach us more about the enzymes we might be able to use in the future to recycle plastic. These enzymes come with their own challenges. Some work in a narrow temperature range, others are just kind of slow.

But the more scientists learn about how these enzymes work, the more they’re able to improve them— sometimes even combining different enzymes to make one big super plastic-digesting enzyme. This is all necessary research, urgent against the backdrop of every other way our planet has been affected by human behavior. We are still only just beginning to understand how widespread this evolution around plastics is, and how organisms have managed to develop mechanisms around seemingly unnatural materials that we’ve overwhelmed nature with.

In 2020, we knew of about 90 microbes capable of digesting plastic, though scientists are still trying to understand whether all those microbes consume the parts we want them to. And more research searching for signs of plastic-digesting enzymes found a correlation between the abundance of those enzymes and the extent of plastic pollution in a given area. Perhaps if we understand more about how microbes are adapting to this pollution, we’ll understand better how we can use them.

But what does it mean to rely on our oldest, smallest creatures to fix our newest, biggest problems? A bacterium can eat away at plastic, but what comes after? When you think of the scale of what bacteria have done in the past, it seems possible for them to fix things for us.

They’ve reshaped atmospheres and constructed ecosystems, what’s a little plastic to them? But for all bacteria can do, they can’t run our business. Nor can they command our infrastructure or curb our demands.

Bacteria are not going to be our saviors, they are simply our neighbors, along with everything else on earth. So to make the best use of them then requires more than just understanding how they work. It requires understanding ourselves, and how we work.

Anything else, and it may not matter what we find. Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you again to Babbel for sponsoring this episode of Journey to the Microcosmos.

Are you ready to step out of your winter hibernation and get ready for summer travel!? Usually trying to learn a new language requires a lot of time and commitment, making it difficult to quickly get into conversations. Well, Babbel is a language learning app that helps you use a new language in real-life situations after only five hours of practice and it offers lessons in 14 different languages.

It’s the #1 language learning app in the world, and with its short, interactive, 10 minute lessons, Babbel teaches more than just vocab words. It teaches you about the culture, people, history and more associated with the language you are learning. And Babbel offers multiple ways to learn, including podcasts, games, videos, and live classes so you can choose whatever format works best for you.

As a Microcosmos viewer, you’ll get up to 60% off when you sign up using our link. Plus Babbel comes with a 20 day money back guarantee, so you can see where Babbel takes you on our language learning journey. The people on the screen right now, they are our Patreon patrons, the people who allow us to continue this exploration of our marvelous world with some really fantastic equipment and a lot of connections to scientists across the globe.

Thank you so much for supporting us on this journey. It means a lot. If you'd like to become one of these people, you can go to Patreon.com/JourneytoMicro.

If you want to see more from our Master of Microscopes, James Weiss, you can check out Jam and Germs on Instagram. And if you want to see more from us, there's always a subscribe button somewhere nearby.