Mycoremediation is a form of bioremediation in which fungi is used to degrade or isolate contaminants in soil. Mycoremediation can be used in soil that is contaminated with petroleum or diesel oil, because the fungi can reduce the polycyclic aromatic hydrocarbons (PAH).

How it Works

From Paul Stamets’ TED talk:

In Bellingham, WA, a remediation experiment was conducted, where four piles of soil were contaminated with diesel, with a concentration of polycyclic aromatic hydrocarbons (PAHs) of 10,000 ppm.  One pile was then treated with enzymes, one was treated with bacteria, one was treated with oyster mushroom mycelium, and one was untreated, as a control.  The piles were left covered, and after six weeks, three of the piles showed no improvement, while the pile treated with mycelium was covered in hundreds of pounds of healthy mushrooms. 
The mycelium of oyster mushrooms produces enzymes that break hydrogen-carbon bonds, which are the bonds that bind hydrocarbons together.  The enzymes re-manufactured with the hydrocarbons into carbohydrates.  The mushrooms in this experiment were healthy because they had obtained a lot of nutrition by transforming toxic petroleum contaminants into useful mushroom-food.  Additionally, the healthy mushrooms sporulated, which attracted insects, which attracted birds, which brought seeds, and the mushroom pile became an oasis of diverse life.  Upon testing, the PAHs in the soil pile had gone from 10,000ppm to less than 200ppm in sixteen weeks, suitable for landscaping use along highways (Stamets 2008).
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Figure 1. Mycoremediated soil (Image: Stamets, 2005)

From “Oil Spills and Mycoremediation” by Paul Stamets:

“Mycelium more readily degrades lower molecular weight hydrocarbons”, but mycelium’s enzymes can reduce the heavier hydrocarbons into lighter ones, allowing for staged mycoremediation treatment.  Aged mycelium mixed with compost shows significantly greater results in hydrocarbon decomposition.  Success rates are greater in nitrogen- limited environments.  Generally, mycelium inoculations in the spring have a greater success rate than inoculations in the fall, because the mycelium has a longer time to develop.

There are many unanswered questions and avenues to be explored in this topic, including: what other species besides oyster mushrooms could be used?  Could mycoremediation mushrooms be safe to eat?  Could the remediated soils be suitable for food crops?  Further funding and research is needed.  (Stamets 2010)