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Discovered in 2011 by researchers from Yale University, Pestalotiopsis microspora is a fungus capable of digesting polyurethane plastic even in the absence of oxygen. This remarkable property makes it a potential ally in the global fight against plastic pollution. A natural and promising path toward a cleaner future.

In 2011, during a scientific expedition in Ecuador’s Amazon rainforest, Yale students stumbled upon an unusual fungus. Hidden within the tissues of certain plants in Yasuní National Park, Pestalotiopsis microspora revealed a unique ability: it can break down one of the most common types of plastic, the polyurethane, even in completely oxygen-free environments.

Though still little known to the general public, this discovery immediately caught the attention of biologists and environmentalists. Why? Because polyurethane, used in many everyday items such as insulating foams, shoe soles, car parts, mattresses, paints and adhesives, is a non-biodegradable plastic. It can persist for hundreds of years in landfills, where it accumulates without breaking down. Finding an organism that can “feed” on it could be a game-changer in the battle against plastic waste.

Unique Digestive Power

The secret lies in the fungus’s metabolism. Pestalotiopsis microspora produces specific enzymes, particularly a type of hydrolase, capable of breaking the chemical bonds in polyurethane. Once those bonds are broken, plastic is reduced to simpler molecules that the fungus can absorb as a source of carbon and energy.

Even more impressive: it can do this in anaerobic conditions, i.e. without oxygen. That makes it especially useful in deep landfill layers, industrial sludge or buried environments, where oxygen is scarce or absent – precisely where plastic waste tends to persist the longest.

For Yale researchers, this biological aptitude immediately suggested potential applications in bioremediation. By introducing such fungi into polluted environments, we could accelerate the degradation of plastic waste and lessen its impact on soil and groundwater.

But the Amazonian fungus is not one of its kind. Other fungal species have also shown the ability to break down plastics. Aspergillus tubingensis, for instance, can fragment polyester in just a few weeks. The oyster mushroom, an edible fungus, is used in both scientific and artistic experiments to degrade UV-treated plastic films.

Still, Pestalotiopsis microspora remains the only known fungus able to degrade polyurethane without oxygen, giving it a significant edge over its fungal relatives.

Promises and Limitations

This discovery paves the way for new waste treatment approaches, more natural and potentially less costly than current industrial methods. Instead of incinerating or landfilling waste, why not compost it biologically using organisms like Pestalotiopsis microspora?

However, several challenges hinder its scaling up.

First, lab tests are still far from replicating real conditions of a landfill or waste treatment plant. The fungus needs specific conditions to thrive: moisture, temperature, pH levels… all of which are hard to control in the open or in polluted environments.

Second, this fungus feeds exclusively on polyurethane. Plastic waste, however, comes in many forms: polyethylene, polystyrene, PVC, PET… each requiring different treatment. So far, there is no “universal” fungus that can digest all plastic types.

Finally, using exotic microorganisms does not come without ecological risk. Introducing Pestalotiopsis microspora into a non-native environment could cause imbalances or even become invasive. One solution might be to produce its enzymes in vitro or to replicate their action in contained bioreactors.

A Natural Path for Tomorrow

Despite its limitations, Pestalotiopsis microspora represents a promising path in the search for ecological solutions to the plastic crisis. Its discovery is also a powerful reminder of the importance and untapped potential of tropical biodiversity.

Each year, more than 400 million tons of plastic are produced worldwide. Less than 10% is recycled. The rest is incinerated, buried or abandoned in nature. While reducing plastic production and improving recycling remain essential priorities, harnessing natural microorganisms could offer a complementary, efficient, low-energy path forward.

That is, if we invest in research, test these solutions at scale, and remember that fungi are not magic wands, but tools among others for building a less plastic-dependent world.

Main sources: Yale Alumni Magazine, Futura Sciences, Treehugger, Earth.org, La Dépêche, Lamycosphere, SciencePost.