Scientists Are Trying To Harness The Power Of Fungi To Decompose Plastic

We have all grown up hearing about plastic's danger to the environment. Not only does it rely on fossil fuel for its primary input, but it consumes too much energy to produce. Of course, that's just the beginning. Even the "recyclable" or "biodegradable" plastics have not lived up to their billing. Less than 10% has been recycled, and plastic production will account for 19% of the global carbon budget by 2040.

But the environmental crisis is not without potential remedies, and the planet is capable of miraculous feats of regeneration. Humans might have pioneered the destructive use of plastic, but an unexpected hero could potentially clean up the mess. Of all things, fungi may be able to undo some of plastic pollution's damage to the environment.

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How Fungi Interact With The World Around Them

Fungi are strange. Like plants and animals, they constitute their own kingdom and have unique qualities that set them apart. The word fungus might conjure images of delicious (or repulsive!) mushrooms as a nutritious addition to a balanced diet. Since mushroom caps often sprout from the ground, we generally assume they are plants. But the cap is really just an analog to fruit, whereas the actual organism is the mycelium, an (almost infinitely) complex tangle of filaments akin to a root system.  

Indeed, mycelia often associate with root structures. Scientists believe that up to 90% of plants co-evolved with subterranean fungi and could hardly live without them—their roots would not function effectively without fungi to help them take up nutrients from the soil. So what do the mycelia get in return from the plants? Carbon—all life needs it. 

So, what does mycelium do, exactly? Two things. First, it secretes enzymes and other chemicals that break organic (i.e., carbon-based) materials into their constituent, non-organic parts, decomposing them. Second, the mycelium grows, sending out more filaments to seek yet more carbon and adhering to the remains of its original food to form a composite.  

For some species of fungi, their enzymes are powerful enough to break down the complex hydrocarbons that comprise plastics. In fact, some can do it in an anaerobic (i.e., oxygen-free) environment, raising the possibility of underwater application. Remember, Russian cosmonauts found fungi on the exterior of a Mir space station window! So, the main question is: can we harness mycelia to break down hydrocarbons (plastics, oil spills, etc.) and render them safe for the environment?

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Examples Of Plastic-Eating Fungi

There are an unknown number of fungal species, but some scientists believe there are over three million. Of the known ones, some have evolved the capability of decomposing even the most complex organic materials. It turns out that there are over 200 known fungi capable of breaking down plastics. Some are exceedingly rare, but others are widespread, removing one of the barriers to wide-scale deployment as a form of "biological remediation" of plastics pollution.

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The Amazon Strikes Back

In 2011, a team from Yale found a rare mushroom in the Ecuadorean Amazon named Pestalotiopsis microspora. Although it produces normal-looking brown mushrooms, the mycelium of this species can feed on polyurethane, one of the most common polymers in consumer plastics. Moreover, it can comfortably survive even when polyurethane is its only carbon source.

Also notable is the fungus' ability to digest polyurethane, whether there is oxygen in the environment or not, opening the door to underwater application. Finally, Pestalotiopsis microspora can clear plastic in a matter of weeks—much faster than other fungi that feed on the same polymer.  

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Turning Plastic Waste Into An Edible Treat

The microbiology department at Utrecht University teamed up with a designer named Katharina Unger in 2014. Their project used edible split-gill and oyster mushrooms to decompose plastics in seaweed-derived gelatin. Astoundingly, the mycelia digested the plastics so thoroughly that there was no trace of any toxins in the final composite of mycelium and seaweed. Moreover, it was edible—with hints of anise or licorice. However, other similar experiments yielded mycelia that still had traces of toxins in them and were unfit for consumption.

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Mycoremediation Could Be The Future Of Plastic Clean-Up

Thanks to the powerful enzymes many fungi produce, they have adapted to harvest carbon from complex and difficult-to-break-down materials, including plastics, pesticides, and herbicides. Deployment of fungi to clean up existing pollution is called mycoremediation, and the theory behind it is undoubtedly practicable on a small scale. 

However, more research is required into the potential environmental effects of introducing non-native fungi to an area with plastic pollution. It may not do more harm than good, on balance, but the ecological side effects are impossible to calculate at this point. Nevertheless, fungi can decompose plastic, and scientists worldwide are working to devise ways of bringing it to market as a cheaper, safer, and environmentally friendlier way of addressing plastic pollution.

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Key Takeaways 

• Reduce consumption—Mycoremediation might be an excellent way to eliminate plastic pollution, but it would be better if we used less, to begin with, especially single use. Do your best to refuse plastic cutlery, straws, and other items when you dine out.
• Cook more—Generally, cooking meals of whole food ingredients requires much less packaging than processed meals, which is a great way to resource use, plastic or otherwise. It's healthier too!
• Support green legislation—Many cities have banned or levied taxes on plastic bags and other items. Of course, nobody loves to pay them, but that's the point. To get out of them, people will buy alternatives to plastic.