A plastic-eating fungus in the Amazon: promise, hype and hard questions

A plastic-eating fungus in the Amazon: promise, hype and hard questions | Photo: Emily Bernal

When a group of Yale undergraduates headed into the Ecuadorian Amazon as part of a field course, they did not expect to stumble across a potential tool in the fight against plastic pollution. Yet from plants collected in the Yasuni National Park they isolated a modest endophytic fungus, Pestalotiopsis microspora, that turned out to do something remarkable: it can grow on, and break down, a common plastic, polyester polyurethane.

Who is behind the discovery?

The key work was carried out within Yale University’s “Rainforest Expedition and Laboratory” programme, led by microbiologist Scott Strobel and colleagues. Undergraduate student Jonathan R. Russell and a team of classmates systematically cultured fungi living inside rainforest plants and then screened them for their ability to degrade synthetic polymers.

Their results were published in 2011 in Applied and Environmental Microbiology in a paper titled Biodegradation of Polyester Polyurethane by Endophytic Fungi. The authors demonstrated that a group of endophytic fungi collected in the Amazon contained strains capable of degrading polyurethane, with P. microspora showing the most significant activity.

What exactly can Pestalotiopsis microspora do?

Polyurethane is used in foams, coatings, adhesives and sealants. It is durable, difficult to recycle and tends to persist for years in landfills. The Yale team showed that certain strains of P. microspora can use polyester polyurethane as their sole carbon source – in other words, the fungus can live on polyurethane without any other nutrient supply.

Several aspects of the work stand out:

·       Endophytic lifestyleP. microspora is an endophyte: it lives quietly inside plant tissues, often producing enzymes that break down tough organic materials. This background helps explain why some members of its genus can also attack synthetic polymers.

·       Growth on polyurethane filmsIn the laboratory, thin sheets of polyurethane were placed into culture. Several fungal species showed some effect, but P. microspora was the one that consistently colonised, etched and degraded the surface over the course of several weeks.

·       Activity without oxygenOne of the most striking observations was the fungus’s ability to degrade polyurethane in anaerobic conditions. This is significant because many landfill environments are oxygen-poor, and very few plastic-degrading organisms are active under such conditions.

·       Mechanism of actionThe fungus secretes enzymes that cleave the urethane and ester bonds within polyurethane. While the precise enzyme families require more research, hydrolases and esterases are the main candidates.

It is important to clarify that, so far, the evidence only supports efficient degradation of polyester-based polyurethane. No strong evidence yet shows that the fungus can effectively break down PET, PVC, polyethylene or other plastics.

How strong is the experimental evidence?

The Yale study quantified the physical and chemical changes in polyurethane films exposed to the fungus. These included mass loss, weakening of mechanical structure, and visible pitting under the microscope. The process took place over weeks, under controlled temperature and humidity.

Follow-up studies have confirmed that fungi in the Pestalotiopsis genus can degrade polyurethane and have begun to characterise some of the enzymes involved. However, research remains limited compared with what is known about other plastic-degrading microbes.

Prospects for waste-treatment applications

1. Landfill and dump-site remediationBecause P. microspora can function in the absence of oxygen, it raises the possibility of treating buried polyurethane waste in landfill environments. Yet this idea remains speculative. Real-world landfills are highly variable and difficult to control, and any introduction of organisms must be assessed for safety, competition with native microbes and potential changes to groundwater chemistry.

2. Industrial bioreactorsThe most realistic application in the near future lies in controlled industrial systems. Polyurethane waste could be shredded and processed in bioreactors containing fungal cultures or isolated enzymes. These environments can be optimised for temperature, pH, moisture and nutrient conditions, making them far more promising than open-environment deployment.

3. Enzyme and gene miningMany researchers see P. microspora as a source of genetic material rather than a ready-to-use organism. Its enzymes could be isolated and used directly, or the genes responsible for degradation could be introduced into microbial strains that grow faster and are easier to manage in industrial systems.

Hype versus reality

The narrative surrounding the discovery – a remote rainforest, a group of students, a fungus that “eats plastic” – captured global attention. But the reality requires nuance. The fungus is an exciting proof of concept for biological polyurethane degradation, not a magic solution to global plastic pollution.

A cautious optimism

The discovery is scientifically robust and opens a promising line of research. It highlights the importance of biodiversity and the potential hidden in underexplored ecosystems. Still, turning this finding into a practical waste-management technology will require extensive research, engineering and regulatory evaluation. Even if successful, it will complement – not replace – broader efforts to reduce plastic production, redesign materials and adopt responsible waste policies.

Sources (with functioning links):

·       Phys.org – Amazon fungi that eat polyurethane: https://phys.org/news/2012-02-amazon-fungi-polyurethane-oxygen.html

·       Mongabay – Fungus from the Amazon devours plastic: https://news.mongabay.com/2012/02/fungus-from-the-amazon-devours-plastic/

·       Earth.org – Plastic-eating mushroom of the Amazon: https://earth.org/plastic-eating-mushroom-of-the-amazon-and-ecuadors-development-dilemma/

·       Beaty Biodiversity Museum – Plastic-eating fungi found in the Amazon: https://beatymuseum.ubc.ca/2013/12/11/plastic-eating-fungi-found-in-the-amazon-may-solve-worlds-waste-problem/

·       Original research, Applied and Environmental Microbiology – Biodegradation of Polyester Polyurethane by Endophytic Fungi: https://journals.asm.org/doi/10.1128/AEM.01768-11

·       Wikipedia EN/FR/PT summaries on Pestalotiopsis microspora: https://en.wikipedia.org/wiki/Pestalotiopsis_microspora