Could plastic-eating mushrooms fix our waste woes?

You may be familiar with celebrity hallucinogenic fungi that contain the trippy compound psilocybin, or perhaps the nutrient-packed lion’s mane and chaga making their way into lattes and supplements. But behind the scenes, scientists are also studying how certain types of fungi can aid in remedying the mounds of plastic pollution in soil and water around the globe.

Scientists have identified around 400 species of fungi that can break down petroleum– or plant-based plastic, which could allow it to be used to make new materials.¹ 

This discovery comes at a critical time, as governments and businesses worldwide reckon with the inefficiencies, high costs, and technical limitations that have put recycling rates at an all-time low. Along with other nature-sourced tools like bacteria and insects, future composting and recycling facilities could put fungi to use to degrade plastics and even help make new ones.

What are plastic-eating mushrooms? 

What’s generically referred to as “plastic-eating mushrooms” are certain species of fungi that microbiologists have found can break down popular plastics like polyurethane and polyethylene. Polyurethane is put into lots of consumer items like clothing, insulating foam, and appliances. Polyethylene, which often goes into food packaging, is the most commonly used plastic in the world.

It isn’t totally clear why fungi are so good at this task. They don’t necessarily munch on plastic as a food source, as is the case with some bacteria. One potential explanation: Fungi have found ways to exploit these materials. For example, these microbes can latch onto plastic for a while in the wild because they tend to last longer than many natural materials and repel water—a rare trait in nature. Plastic out in the wild offers “a distinct set of properties that microorganisms explore and use,” making it pretty different from the substances they evolved to inhabit, says Irina Druzhinina, a senior research leader at the Royal Botanic Gardens, Kew in England. 

How do plastic-eating mushrooms work?

Researchers have observed how some fungi species can gobble up certain varieties of petroleum-sourced polymers, or the long chains of carbon and hydrogen atoms that often compose plastic.² The plastic-eating mushrooms kick things off by releasing enzymes, or proteins that speed up chemical reactions, to degrade these polymers. Various types of enzymes secreted by fungi can break down the polymers into smaller units called monomers.³ But how are they able to feast on materials that only entered mass production after World War II? 

Out in nature, some fungi degrade organic materials like dead plants and animals, so they evolved the skills to tear apart polymers with structures somewhat like those found in plastic. It turns out that the group of enzymes long used by fungi to deteriorate lignin, a natural polymer found in the cell walls of most plants, work well on degrading mass-produced plastics polyethylene (PE) and polyvinyl chloride (PVC). The same seems to be true for other plant-degrading enzymes called esterases, which can help fungi eat the plastics polyethylene terephthalate (PET) and polyurethane (PUR).⁴

Sounds great, right? But it’s an imperfect solution. Fungi can take days or even months to degrade plastic, and it may leave tiny pieces of plastic behind when it’s done—a problem researchers will have to address in coming years.⁵

What are the types of plastic-eating fungi? 

While researchers have found almost 400 types of fungi that can break down plastic, certain ones have attracted loads of attention for their unique, efficient abilities. 

Pestalotiopsis microspora

The fungi that started it all. Early work on the Pestalotiopsis genus sent scientists down the plastic-degrading fungi rabbit hole. In 2011, Yale University scientists announced they had found that several fungi from the Pestalotiopsis genus turn polyurethane (PUR) plastic into organic matter within lab environments.⁶ Two species could survive on a purely PUR diet in settings without any oxygen—meaning that they could get to work in oxygen-free landfills, where this type of plastic quickly piles up and can take decades to disappear. Pestalotiopsis fungi were also able to nom on plastic suspended in liquid, suggesting they could be deployed to the ocean to eat up plastic pollution. The species Pestalotiopsis microspora did a particularly great job of breaking down PUR: In two weeks and degraded it completely.

Pleurotus ostreatus

Commonly referred to as the oyster mushroom, this fungi makes for a tasty dish for us humans—but it can also chomp efficiently on plastic. In early 2023, a Nigerian team of researchers announced that Pleurotus ostreatus and its cousin Pleurotus pulmonarius successfully degraded polyethylene terephthalate (PET), a super-durable, tough-to-degrade plastic that’s one of the most widely used worldwide (it’s often put into fabrics and food packaging).⁷ 

P. ostreatus has also been found to break down mixes of plastics in diapers and sanitary pads containing the polymers polyethylene and polypropylene.⁸ This is important because it’s often tricky to recycle items that incorporate multiple types of plastics. In addition to conventional types of plastics, research has suggested that P. ostreatus can be effectively unleashed on plant-based plastics and spit out byproducts like carbon dioxide and water.⁹

Schizophyllum commune

In 2014, Austrian designer Katharina Unger announced a nifty idea: A device that can digest plastic waste and turn it into edible materials. Working with scientists at Utrecht University in The Netherlands, Unger aimed to feed plastic to P. ostreatus and a mushroom species called Schizophyllum commune to help them grow into a delicious meal. 

Scientists have since demonstrated how S. commune, which grows on dead wood on every continent (except Antarctica), can degrade plastics like polyethylene and synthetic polymers called phenolic resins thanks to its wood-munching abilities.¹⁰

Aspergillus tubingensis

This moldy fungus belongs to a genus with several promising plastic-colonizing candidates. A 2017 study reported that Aspergillus tubingensis sourced from the soil at a waste disposal site in Pakistan could completely degrade polyurethane into smaller pieces within two months.¹¹ A. tubingensis’ relatives have some impressive skills, too. After treating the polymer with heat or UV light, A. terreus reduced samples of polypropylene by up to 25 percent over a period of 90 days in the lab, according to a study published in early 2023.¹²

Is this a realistic solution for plastic pollution? 

Plastic-eating mushrooms aren’t the answer to our waste problem—at least, not yet. Right now, fungi work pretty slowly and have only been shown to work with a few types of polymers.¹³ And just because things have worked out in some tightly controlled lab conditions, doesn’t mean that they’re a sure-fire solution to combat plastics out in the wild or at an industrial facility. Scientists typically work with simplified versions of these polymers, but the products we use and dispose of every day also include chemical additives like hardeners, so it’s not clear how fungi would perform on these other ingredients. 

What would need to happen for this to become part of the recycling process? 

For this to work in our existing recycling processes, the technique needs to get much faster and efficient. Researchers are working on isolating the plastic-hungry enzymes fungi produce, along with other natural tools found within fungi and other microorganisms, and some are trying to engineer them to speed things up. 

But before they can determine precisely which ingredients to extract and engineer, they need to keep studying the fungi as a whole and pinpoint what makes them so good at eating plastic. This work involves studying the DNA of multiple microbes at once, including different types of fungi and bacteria, for a zoomed-out view of all the different useful enzymes and other components out there among tiny organisms, Druzhinina says. 

Scientists are also trying to figure out whether applying heat, UV light, or other pre-treatments can make fungi better at this task. “There is still much work to be done before it becomes attractive for industry and consumers,” she says. “However, there are many of us, and we hope that harnessing new technologies such as DNA sequencing and AI will lead to reasonable results within the next decade.”

1. Insights into the mechanisms involved in the fungal degradation of plastics, Ecotoxicology and Environmental Safety, Sep. 2023 ↩︎
2. The distinct plastisphere microbiome in the terrestrial-marine ecotone is a reservoir for putative degraders of petroleum-based polymers, Journal of Hazardous Materials, Jul. 2023 ↩︎
3. Wood decay fungi show enhanced biodeterioration of low-density polyethylene in the absence of wood in culture media, PLoS One, Jul. 2023 ↩︎
4. Fungal enzymes involved in plastics biodegradation, Microrganisms, Jul. 2022 ↩︎
5. Biodeterioration of pre-treated polypropylene by Aspergillus terreus and Engyodontium album, NPJ Biomaterials Degradation, Apr. 2023 ↩︎
6. Biodegradation of polyester polyurethane by endophytic fungi, Applied and Environmental Microbiology, Aug. 2011 ↩︎
7. Polyethylene terephthalate (PET) biodegradation by Pleurotus ostreatus and Pleurotus pulmonarius, Environmental Monitoring and Assessment, Apr. 2023 ↩︎
8. Biotic degradation of plastic hygiene products by using Pleurotus ostreatus, IOP Conference Series: Earth and Environmental Science, Dec. 2020 ↩︎
9. Degradation of green polyethylene by Pleurotus ostreatus, PLoS One, Jun. 2015 ↩︎
10. Decaying hardwood associated fungi showing signatures of polyethylene degradation, BioResources, 2021 ↩︎
11. Biodegradation of polyester polyurethane by Aspergillus tubingensis, Environmental Pollution, Jun. 2017 ↩︎
12. Biodeterioration of pre-treated polypropylene by Aspergillus terreus and Engyodontium album, NPJ Biomaterials Degradation, Apr. 2023 ↩︎
13. Fungal enzymes involved in plastics biodegradation, Microrganisms, Jul. 2022 ↩︎