Mushrooms Break Down Oil and Plastic in Bioremediation

Imagine walking through a forest. It’s a dim, overcast morning, and the ground is moist from days of raining. As you walk beneath the arboreal canopy, you spot something interesting on the ground. It’s not a plant, it’s not an animal…it’s the brightly colored cap of a freshly sprouted mushroom! Your first instinct is to wonder whether or not it is poisonous, but if you happen to have a mycologist with you, you would quickly find out that mushrooms can be very valuable to our ecosystem.

In fact, mushrooms are now being explored in new ways, and in particular for a process called bioremediation. In simple terms, this means they are being used to break down harmful materials such as oil and plastic.

Mushroom Facts

Mushrooms aren’t like plants, and a single mushroom does not constitute an entire organism. The mushroom itself is not even the body of the organism, it is the fruit. Like a strawberry or a watermelon, the mushroom carries the seeds (spores) that will disseminate in the environment. The real organism is buried beneath the soil, comprised of a vast branching network of cells known as the mycelial network.

This mycelium is what decomposes organic compounds, returning nutrients to the soil and releasing CO2 for plants to breathe. As the mycelium (a single thread is known as a hyphae) spreads outward, it releases enzymes, which break down long-polymer chains into their basic subunits, such as sugars. These smaller molecules are then absorbed through the walls of the hyphae. The interconnectedness of the mycelial network allows for both a rapid breakdown of organics in soil, and a swift distribution of the nutrients throughout the network. Mycelial colonies are extremely resistant to micro-organisms and physical damage. No single area of the network is vital to another, so if a section gets damaged, the network either sacrifices it or works quickly to repair it. There is also no limit as to how large these networks can grow. In fact, one of the largest organisms in the world is an underground mycelial mat spanning 2,400 acres (or 1,665 football fields) in eastern Oregon. The mat is believed to be over 2,200 years old. A small sample is shown in the micrograph below.

Mycologist Paul Stamets has been pioneering the research of mushrooms in discovering their use in bioremediation and antibiotics, because the ability of mycelia to produce enzymes which break down long chains of hydrocarbons is unique. No other organism is as efficient at producing and distributing these enzymes. In fact, mycelia are so efficient that a mycelial colony is capable of restoring soil saturated with toxic oil and other hydrocarbons in just a few months.

As a result of one experiment, in which bioremediation groups were tasked with reducing a pile of contaminated soil to a reusable state, Paul Stamets discovered a special strain of oyster mushroom that was highly efficient at breaking down the PAHs (polycyclic aromatic hydrocarbons) found in oil and petroleum. It took merely four weeks for the mycelia to build a network and overtake the contaminated soil. Large oyster mushrooms grew straight out of the dirt, some of the caps reaching a foot in diameter! This massive explosion of mushroom fruit bodies attracted innumerable flies and insects that made the mound of dirt their home, and the previously contaminated soil became its own life-sustaining habitat. The insects brought birds, the birds brought plant seeds, and the plant seeds sprouted and flourished after the mycelium had detoxified the soil and provided essential nutrients for them to grow.

This breakthrough in myco-technology, if pursued, has many beneficial ramifications. Managing fossil fuel waste has been a huge topic within the environmental industry in recent years. Companies that burn fossil fuels usually stockpile their waste until it is relocated or buried in the ground, causing further contamination risks. Another concern is that contaminants from plastic bottles and bags buried in landfills can leach into the soil and water table.

Magic Mushrooms

Most fossil fuel waste contains a significant amount of PAHs, a prime source of energy for mycelia. Mushrooms could be used to significantly decrease the toxicity of this waste by inoculating it with the proper strain. While this would still leave mineral contaminants such as arsenic, barium, and manganese, many of the PAH carcinogens would be removed. And, in the search for sustainable energy and biomass fuels, it is important to remember what can be done to reduce the impact of current fuels on our environment.  Bioremediation is one solution that is making a lot of headway.

As an example, many companies are beginning to utilize biodegradable plastics derived from corn starch and sugarcane. Biota bottled spring water is one: Their water bottles are made completely from corn which is fully compostable. For Biota bottles and all other compostable products, mushroom mycelia are an excellent aid in the breakdown process. Not only do mycelia catalyze the composting of these plastics, they promote healthy soil at the composting sites, and produce mushroom fruits that could be used for medicinal and culinary applications. In dense city areas, it can be quite difficult to find a region in which plastics biodegrade quickly. By introducing mushroom mycelia, though, compost sites could be placed virtually anywhere — even indoors or underground — as the mycelium does not require light to grow.

Other provocative mushroom discoveries by Stamets include a new biofiltration process known as mycofiltration, a fungal strain capable of wiping out termite and carpenter ant colonies, and strains that produce metabolites effective against human pathogens such as pox and flu viruses. Some of these strains grow naturally in old growth forests around the USA, and Stamets has been able to get approval from the USA’s Department of Defense to declare these forests national protected land areas as a matter of national defense.

While the mushroom may still seem a bit mysterious, there appears to be at least one man asking the right questions. What else can this beautiful organism do for the planet?

References:

Fungi Perfecti. http://fungi.com. Accessed February 2009.
Stamets, Paul (2003). Mushroom Power. http://www.yesmagazine.org.  Accessed February 2009.