Mushrooming problem

I don’t struggle with insomnia often, but when I do, it apparently leads to having a breakdown and crying in my bed whilst watching a documentary about landfills at 4:30am on a Tuesday. Luckily for me, that same day that happened I read a revelatory chapter in Merlin Sheldrake’s Entangled Life on mushrooms capable of digesting plastic, pesticides, explosives, cigarette butts, and crude oil. I ended up staying up that night too, trying to understand why we aren’t using mushrooms that break down plastic and tangentially reading about mycelium packaging.

Admittedly, it is impossible to imagine our modern lives without plastic: it gives us our food packaging, clothes, flooring and insulation, furniture, cables, shoes, sewage pipes, rubbish bags, medicine containers, car parts, and electronics. From where we are, it is hard to imagine a future without plastic. But plastic production has more than doubled in the last two decades, and of the 500 million tonnes produced each year, only 9 per cent is recycled. Half of the world’s plastic goes directly to landfills — in the US, it’s three-quarters. The reason we need and use plastic so widely is also the reason it is so environmentally noxious: it resists natural degradation.

For the past decade, various fungi have been making headlines for their ability to break down plastics, beginning with the Pestalotiopsis microspora discovered in Ecuador in 2011 or the Aspergillus tubingensis discovered in Pakistan in 2017. The grassroots research that has since expanded is called “mycoremediation.” In total, scientists have discovered over 400 species of fungi and bacteria that can degrade plastic. Some species, like Pestalotiopsis fungi, are able to decompose in anaerobic conditions, ideal for oxygen-poor landfills. Others, including the common edible oyster mushroom, can break down plastic and produce in its place an edible fruit. Research on what is essentially advanced experimental composting takes an ecological view of our philosophy and systems of waste to conceive of alternative by-products fungi could be used to make.

Fungi play a critical role in the decomposition of organic matter in natural environments, transforming a substance from one form to another. The various enzymes they produce take apart intricate organic compounds like proteins, which are made of polymers. Polymers are lengthy chains of atoms linked together that produce naturally occurring materials like silk, keratin, rubber, and silk. Synthetic polymers include nylon, polyester, and Teflon — man-made materials we call plastics. The length of the polymer chain gives these materials their durable and flexible properties. Fungi have evolved specialised mechanisms to recycle essential nutrients into the soil by disintegrating natural polymers such as cellulose. They are the only major organisms that can break down lignin, the main component of plant cell walls and wood.

It would be just as dangerous for us to lose plastic’s “indestructible” nature, should it ever become perishable

The vision of an intentional partnership with fungi is a compelling one. We can imagine a future where households feed a “pet” mushroom or contribute their waste to community recycling centres powered by fungi. Bioremediation — using living organisms to eliminate or neutralise environmental pollutants — offers an appealing alternative to conventional recycling methods, which are often energy-intensive and inefficient. But large-scale industrial utilisation depends on our ability to accelerate naturally slow processes and, given that fungi reproduce by releasing some 50 million tons of spores into the air each year, set sufficient safeguards to prevent domesticated fungi from becoming aggressively invasive. There is a reason plastic use is so widespread: it is incredibly good at keeping medical instruments sterile, preserving food in a meat packing facility, and insulating wires underground. It would be just as dangerous for us to lose plastic’s “indestructible” nature, should it ever become as perishable as any other organic matter.

How far are we from having biodegrading fungi manage our toxic waste? We’ve been trying for a while and we’re getting closer. In 2015, Julia Kaisinger and Katharina Unger were awarded the prestigious BraunPrize Sustainability Award for their “Fungi Mutarium”, an installation developed to convert plastic waste into food. Since 2011, the French company Carbios has been developing an industrial method to recycle PET, the primary plastic used in bottles and food packaging, using a bacterial enzyme. They turned their developmental research into a commercial plant in 2021, and by 2026 will be able to handle up to 50,000 tonnes of PET waste annually, the equivalent of 2 billion bottles. Startups like Mycocycle, which uses white-rot mushrooms to transform construction waste into new materials, are probing the potentialities of bioprospecting, industrial solutions derived from natural sources. But the scalability of these fungal solutions remains curtailed by the limitations inherent to the natural process. We have to think about which strains can digest which plastics, what optimal conditions need to be kept for them to grow, how the plastic can be treated to speed the process, and how to safely use the byproduct. It is not impossible to do, but the resources funding such research is lacking.

You can grow your own Pestalotiopsis microspora and feed it your plastic, but the natural process of degradation is very slow. It helps if you shred the plastic and treat it with UV radiation (e.g. cook it under a high-powered black light until it becomes brittle to break down the plastic). If you succeed, don’t eat it. It is still unclear to what extent their biomass is safe for human consumption or free from harmful byproducts such as nanoplastics. But it’s a wonder-inducing thought or lab experiment, even if transitioning to integrating fungal bioremediation into existing systems is still some decades away. As Sheldrake says in his book, “all life-forms are in fact processes not things.”