Mycoremediation: Cleaning Up with Fungi That Eat Plastic

Human activities have left a detrimental impact on our environment – from oil spills leaking into the ocean to tons of plastic products overwhelming our landfills. Even if we were to alter our habits completely, much of the damage we have caused cannot be fully reversed. Researchers have tested numerous techniques to reduce the amounts of contaminants and pollution in our environment, but many of these methods are expensive and time-consuming, yielding slow results. Fortunately, there may be a solution hiding right below our feet: fungi.

Known for their skills in biodegradation, fungi are typically thought of as organisms that break down organic matter – possibly decaying trees, fecal matter, or dead plants and animals. But different types of fungi can also decompose, filter out, or absorb not only synthetic matter but also toxic compounds and contaminants. Scientists have been using this unique quality in fungi in a process called mycoremediation. This method may help clear our soil and water pollution and tackle our immense plastic problem. 

What is mycoremediation?

Let’s start by discussing bioremediation which is a practice that utilizes living organisms, primarily microbes, to mitigate environmental pollution. The organisms used for bioremediation have natural abilities to decontaminate the water, soil, or air, breaking down pollutants into less harmful forms. 

Within the broader scope of bioremediation is a technique that has gained considerable attention in recent years: mycoremediation. Usually, fungi are known for their ability to decompose organic matter like leaves and dead organisms. However, the unique qualities of fungi have shown great promise in reducing environmental contaminants like heavy metals, crude oils, plastic waste, and other various forms of industrial waste byproducts.

The term “mycoremediation” was coined by renowned mycologist Paul Stamets in 2005. Still, the concept of using fungi to clean up waste has existed for decades before mycoremediation’s growing popularity. Since then, fungi and their abilities to reduce pollution have gained widespread recognition from the scientific community. Researchers have extensively explored numerous fungi species, examining their capacity to break down various forms of harmful pollutants into organic material.

How do fungi degrade environmental contaminants?

To break down any form of matter, be it toxic or not, fungi use their mycelium, which reaches with tiny structures called hyphae into their chosen substrate, excreting special enzymes to break them down into smaller pieces and digest their food. 

Many mushroom species have shown proficiency in degrading several types of materials, including inorganic compounds. Some species of fungi are capable of digesting different types of plastic materials as a food source, such as polystyrene (styrofoam) and polyester fabrics.

They can also break down other complex compounds such as petroleum, pesticides, and herbicides, degrading them into simpler, less toxic byproducts. Fungi’s ability to target and break down compounds that are otherwise difficult to manage makes these organisms a valuable asset to the field of bioremediation.

Benefits of mycoremediation

Mycoremediation has several advantages as a means of environmental remediation. Compared to other current methods, fungi offer a significantly more cost-effective approach. Fungi are inexpensive to cultivate and do not require expensive equipment or materials. They can be grown directly on waste product substrates.

Fungi also grow incredibly quickly and are biodegradable, making them an ecologically friendly technique. They break down pollutants into non-toxic byproducts. Unlike some other remediation techniques, fungi require no harmful chemicals but instead rely on their natural biological processes to clear up waste. Furthermore, fungi can clear up a wide array of pollutants, making them a versatile option for different situations of contamination.

Current applications of mycoremediation

Bioaccumulation of heavy metals and pesticides

Pesticide and heavy metal contamination in soils and pater pose a significant risk to human and ecological health. These pollutants can remain in the environment for several years, leading to long-term, harmful effects. Traditional methods of removing these contaminants include chemical treatments and incineration, which are costly and can release even more toxins into the environment. Fortunately, several recent studies have shown promising results that fungi could help detoxify these hazardous substances from our environment.

According to one study, researchers investigated environmentally friendly methods to clean up heavy metal pollution. They closely examined fungi found in soils from gold and gemstone mine sites for their tolerance to different heavy metals such as cadmium, copper, lead, arsenic, and iron.

The three different fungi from these sites all displayed tolerance to copper, lead, and iron, even at high concentrations. Additionally, two of the fungi had a tolerance to cadmium and arsenic at certain levels. These findings suggest that the tested fungi could potentially be effective in efforts to clean up heavy metal environmental contaminants (1).

Another study isolated and examined different types of saprotrophic fungi from agricultural environments to assess their ability to tolerate and use glyphosate as a food source. Glyphosate, otherwise known as Roundup, is one of the most popular pesticides in the world.

Through different experiments, the researchers identified one fungus capable of degrading glyphosate by up to 80% without experiencing any negative growth effects. This study demonstrates that some fungi can be valuable solutions for addressing pesticide and herbicide contamination (2).

Mycofiltration

Fungi are not only useful for their ability to biodegrade contaminants but also for their capacity to filter them out through their intricate mycelium network. This method is known as mycofiltration. Contaminated water is directed through a network of fungal mycelium inoculated on a substrate like straw or woodchips. As the water passes through, contaminants like heavy metals, microbial pathogens, and fertilizers are removed from the water source. 

One study investigated the effectiveness of mycofiltration in reducing the toxicity of drinking water from rural communities in Delta State, Nigeria. Water from contaminated sources went through a microfiltration filter. After 24 hours of treatment, the data analysis showed a significant decrease and, in some cases, the total elimination of heavy metals and microorganisms in the water samples (3).

Similar studies have demonstrated correlating results, revealing that this technology could be used to affordably filter contaminated water sources, especially in areas with water insecurity.

Radiation cleanup

Five years after the devastating Chernobyl nuclear disaster, the first organisms to grow in the highly contaminated environment were primarily fungi. This species of black fungus called Cladosporium sphaerospermum could tolerate extreme nuclear conditions, including radiation. Despite how dangerous radiation is for most living organisms, these fungi not only thrived in radiation but also fed off of the radioactive remains.

There are many other types of fungi that can use radiation as a direct energy source, called radiotrophic fungi. While most organisms rely on sunlight or organic matter to feed them, these fungi use melanin in their cell walls to absorb radiation and convert it into chemical energy that can be used to fuel them. These fungi have been found in radiation-exposed areas all around the world, from Israel to Antarctica.

One study investigated the potential of several different fungi to uptake radioactive compounds from a radionuclide-containing medium. They found that some of the fungi that were used demonstrated a high efficiency at absorbing radioisotopes. Analysis of these fungi revealed that melanin pigments exhibited a 60% uptake in radioactive compounds, and a significant accumulation of melanin granules occurred prior to treatment (4).

Another study found that some yeast can handle high temperatures and radiation while in low pH environments. Out of the 27 yeasts tested, many of them showed resistance to radiation and heavy metals. The research concluded that many yeasts could play a significant role in cleaning up radioactive waste sites, especially ones that are acidic (5).

Oil spill recovery

Oil spills pose a significant environmental concern in aquatic ecosystems. The compounds in crude oil can deplete oxygen and have toxic effects on organisms since they contain carcinogenic hydrocarbons. This major threat to marine organisms is difficult to clean up and can persist in environments for long periods of time.

According to a study, researchers tested three different edible mushroom species to determine their abilities to metabolize petroleum for remedial purposes. They set up Petri dishes with varying amounts of oil concentrations for each mushroom species. After a twenty-day growth period, the researchers found that a mushroom called Cortinarius violaceus was the most efficient at degrading crude oil for growth, covering over four times the amount of petri area compared to the other tested species.

Furthermore, the fungi reduced the oil content in the Petri dishes by 80%, which researchers attributed to the Cytochrome enzymes that typically break down cellulose and lignin, an organic polymer found in the cell walls of plants. Since crude oil has a similar chemical structure to these substances, the enzymes were able to degrade it in a similar matter (6).

In another study, researchers isolated fungal stains capable of biodegrading crude oil from polluted soil. Using genetic sequencing, they identified three different fungi which could degrade around 50% of the crude oil. Through this study, they found that several species within the Aspergillus genus may be able to tolerate and adapt to crude oil pollutants (7). Both of these studies indicate that fungi can be effective and eco-friendly tools to degrade oil spills that are otherwise difficult to clean up.

Biodegradation of plastic polymers

With over 400 million tons of plastics produced each year, landfills are quickly filling up, and our land and ocean are becoming covered in a material that takes incredibly long to degrade. 

Scientists have been researching how microorganisms like fungi can break down plastic faster to find a solution to this issue. One study looked at over 200 fungal species capable of breaking down plastic based on previous research, noting the relationship between these fungi and comparing their genetic makeup. The researchers found that plastic-degrading fungi belong to three main groups: Ascomycota, Basidiomycota, and Mucoromycota (8). 

Certain enzymes called laccases and peroxidases are usually used by fungi to break down lignin. However, according to research, these compounds effectively degrade specific types of plastics like polyethylene (PE) and polyvinyl chloride (PVC). There are also fungal enzymes called esterases that are capable of breaking down polyethylene terephthalate (PET) and polyurethane (PUR). These enzymes are derived from different kinds of fungi, and in laboratory conditions, they have been proven effective in breaking down plastics (9).

Plastic-eating fungi with mycoremediation capabilities

There are several types of plastic-eating mushrooms that can use synthetic polymers as a food source or substrate. These fungi can break down plastics within a few months, while it takes 20 to 500 years for plastics to degrade naturally. The abilities of these fungi could offer a promising solution to the plastic pollution problem and can be used to develop strategies for plastic waste management.

Oyster mushroom (Pleurotus ostreatus)

Oyster mushrooms are not only a delicious and popular edible mushroom, but they also have shown the ability to break down and consume various plastics with their enzymes. In some cases, oyster mushrooms, used for mycoremediation, could also be consumed as a food source.

Split gill mushroom (Schizophyllum commune)

The split gill mushroom has been known to degrade various plastics, notably polyurethane. Like the oyster mushroom, split gills are edible and, in some cases, can be consumed even after degrading plastic, ultimately clearing up waste while providing food.

Pestalotiopsis microspora

This plastic-eating fungus from the Amazon rainforest in Ecuador was found in 2012 by students from Yale University. Not only can this fungus survive on plastic alone, but it can also live without oxygen, making it a promising means to clear up massive landfills.

Aspergillus tubingensis

Aspergillus tubingensis is found worldwide in regions with warmer climates. It is a resilient fungus, tolerant to low pH and water levels. Like many other fungi in the Aspergillus genus, A. tubingensis can degrade some plastics. A few years ago, researchers found it feeding on plastic in a Pakistani garbage dump, demonstrating its potential for landfill remediation. It was able to break down polyester polyurethane into smaller pieces after two months.

Incorporating mycoremediation at home

Image source: LIVIN Studios

While mycoremediation is still in its early stages of research, the practice can be implemented on a smaller scale in your own home. An Austrian design developing company called LIVIN Studios has created a prototype of the Fungi Mutarium that allows people to grow edible fungal biomass in specially designed agar shapes filled with plastics.

The fungi will digest the plastic and overgrow the entire substrate, leaving behind an edible pod that can be prepared and eaten. Though this ultramodern product is still going through research and is not yet commercially available, it demonstrates the near future of at-home mycoremediation. 

Don’t worry if you can’t access this product yet, because you can utilize mycoremediation in a similar way at a fraction of the cost. A home setting may be challenging to replicate the controlled conditions scientists have used to degrade plastics with mushrooms. Fortunately, you can still grow mushrooms on a variety of household waste products so you can sustainably clear up your rubbish and transform it into a tasty meal.

Fungi grow on many substrates you may already have at home, such as coffee grounds, cardboard, grass clippings, and compost. Oyster mushrooms, in particular, are well-suited for at-home mycoremediation as they can decompose different materials and are delicious to eat. There are different varieties of oyster mushrooms to choose from, but any will do the trick!

To grow oyster mushrooms on household waste, you can purchase the spores online. Before planting them in the waste substrate, you must inoculate them on a grain spawn like rye or brown rice. Once the mycelium has fully colonized the grain spawn, you can mix it with your chosen waste substrate. Over a few weeks, the fungus will transform your household garbage into delicious mushrooms that you can enjoy.

For a detailed guide on how to grow mushrooms from scratch, click here.

To learn more about mushroom composting a recycling waste products, click here.

A greener future, with the help of fungi

Although mycoremediation holds great promise for our environment, it’s important to note that it is still an emerging field of research. Scientists are still working to fully understand the best methods to apply these techniques, which fungi are suitable to use, and the range of contaminants that can be effectively addressed.

We should not rely solely on fungi to do the job for us. We can do our part by reducing the amount of waste we use and produce, such as limiting single-use plastics and disposing of our waste properly. By following more sustainable practices and avoiding substances that can further harm our environment, we can minimize our negative impact on the environment.

Although mycoremediation shows potential in eliminating different forms of waste, it should still be viewed as one part of a larger effort to address pollution and our overwhelming need for sustainability. With the continued collaborative efforts of scientists, policymakers, and everyday people like us, we can hopefully maximize the benefits of mycoremediation and contribute to a greener future for the generations to come on planet Earth.