What if we could find a germ that broke down our plastic waste into tiny building blocks that could be reassembled and recycled again and again, allowing us never to produce another ounce of new plastic again?

That’s the dream that scientists are now pursuing, using bacteria that can, functionally, “eat” plastic. They’re looking into a different strain of bacteria that could break down plastics in the ocean. There’s a fungus that may show promise for breaking down hard-to-recycle food containers. And scientists found, a few years back, that the larvae of a moth that lives in beehives seemed to like to eat plastic bags. 

Current methods of recycling plastic, which largely involve crushing it to break it down, yield new material that is lower quality — and so less marketable — than new plastic. So many companies wind up opting for new plastic, instead of the more expensive, lower-quality recycled product. 

But recycling plastics could chemically break down plastic into components that can be reassembled — and it yields a material that’s exactly the same quality as new plastics. One company says that its process, which uses bacterial enzymes, produces half the carbon emissions that it takes to produce new plastics. 

Recycling with bacteria “fills a gap that other recycling methods can’t do well,” said Elizabeth Bell, a researcher with the National Renewable Energy Laboratory (NREL) in Golden, Colorado. “What remains to be seen is how viable it is at scale.”

The scale of the plastics problem is enormous, and calls for novel solutions. Every day, plastic that could fill 2,000 garbage trucks gets dumped into the world’s waters, according to the United Nations (UN). The plastics that humans have produced worldwide exceed the biomass of all living organisms, according to a 2020 study published in Nature. Of all that plastic, only about 9 percent has ever been recycled. 

In spite of that, plastic production continues to increase year over year: It’s expected to more than triple between 2017 and 2050, according to GRID-Arendal, a Norwegian nonprofit environmental research organization that partners with the UN. 

It’s clear that we need new ways to recycle plastic. And that’s where the bacteria come in. 

Recycling with bacterial enzymes

Japanese researchers, back in 2001, made a startling discovery outside of a bottle-recycling plant in the city of Sakai, according to The Guardian. They found a filmy layer of bacteria, which appeared to be, in a sense, “digesting” plastic. 

When they finally published their research in Science in 2016, it was a blockbuster. The bacteria, Ideonella Sakiensis, named for the city where it was discovered, was the first identified that produced an enzyme that showed promise in breaking down plastic. Since then, scientists have been racing to find the ideal plastic-eating bacteria. 

One French company, Carbios, thinks it might have done so. It’s going to market with a bacterial enzyme that it argues is more efficient than the one produced by the Ideonella bacteria — and betting big that it can make a dent in the plastics crisis. 

The process works by breaking down plastic (a polymer) into its components (monomers), which can then be reassembled into plastic that’s like new. And this process can, in theory, be repeated over and over, without ever sacrificing the quality of the plastic. 

Benedicte Garbil, senior vice president at Carbios, Carbios-Agence SkotchProd

“We are building the first bio-recycling plant in the world,” said Benedicte Garbil, a senior vice president at Carbios. “It will be able to process 50,000 tons of waste per year.” 

“That’s 2 billion bottles or 3 billion t-shirts,” she added. 

That’s a lot of plastic, but it isn’t significant on a global scale. Carbios hopes to license its technology to other companies around the world to facilitate the building of new factories, Garbil said. 

Bell, the researcher with the NREL, noted that the process Carbios uses may be energy intensive — creating carbon emissions as it breaks down plastic. Garbil said that their process, while still requiring energy, was more efficient than creating new plastics. The process required heating plastic to 65 degrees Celsius, but emphasized that Carbios’ process produced just 51% of the emissions of what she called “virgin plastic.” 

There are a handful of other companies in the enzymatic recycling space, including U.S.-based Protein Evolution. But, to Bell, a lot is riding on Carbios. 

“Everybody is watching Carbios, because they’re furthest along,” Bell said. “I think they will be the first definitive test about whether this can work.” 

A plastic-eating fungus

Scientists may colloquially describe bacteria as “eating plastic” but, more precisely, what bacterial enzymes do is take apart plastics like a puzzle, breaking them down into pieces that can be reassembled. 

But we have so much plastic waste that needs to be disposed of, that recycling all these pieces may not be the only solution. 

Meet Aspergillus terreus and Engyodontium album, two common species of fungi that researchers think might help digest our plastic waste. While the fungi won’t recycle the plastic, they could speed up its decomposition. 

Researchers at the University of Sydney found that the fungi could, over a month, decompose about a fifth of the type of plastic used to make Tupperware containers and TicTac packaging.

“Fungi are incredibly versatile and are known to be able to break down pretty much [anything],” said Dee Carter, a mycologist at the University of Sydney and a co-author of the study, in a statement. “This superpower,” she said, allows them to decompose materials “into simpler molecules that the fungal cells can then absorb.”

While this research shows promise, it’s “very early stage,” Bell said, and it isn’t clear what sorts of commercial applications it could have. The researchers at the University of Sydney said they’re looking into that. 

“Watch this space,” said University of Sydney PhD candidate and the study’s lead author, Amira Farzana Samat. 

Could we get baby moths to recycle for us?

Federica Bertocchini, a scientist with the Spanish National Research Council and an amateur beekeeper, plucked wax worms out of her hives and placed them in a plastic bag. The worms, the larval form of the wax moth, are a common pest for beekeepers, as they can invade hives to eat beeswax. A short time later, she found that the worms had chewed through the plastic, according to the New York Times.

She sent the observation to her team, and it prompted research that found that enzymes in wax worm spit could be the only known animal-produced chemical capable of rapidly breaking down plastic at room temperature. 

Researchers hope that studying the chemical makeup of the bug’s saliva might lead to a breakthrough in plastics recycling, especially since many of the other methods for recycling plastics with enzymes require heating the material. 

But other scientists have questioned the researchers’ results, and said it may not prove definitively that the larvae could actually chemically break down plastic. Instead, they argued that the larva might just be chewing it into tiny bits. Or it may be that some chemical breakdown happens but it’s the result of the worm’s gut microbiome — the bacteria that thrive in the bug’s intestinal tract. In either case, scientists are still pursuing these creatures.

Regardless of whether its wax worms, fungi or bacteria that end up making a dent in the plastic crisis (or all three), scientists are continuing to throw ideas at the wall to come up with strong solutions. 

Colorado State University researchers, for example, are looking at ways to create biodegradable plastics by building them from microorganisms that could break apart whether that’s in soil or the sea. And other researchers are looking into whether bacteria could help eat up ocean plastics. 

With a 100,000 ton–heap of plastic twice the size of Texas floating in the Pacific Ocean, and a plastic bag recently found in the deepest part of the sea, one thing is very clear: we’ll need all the solutions we can get.