SHROOM VACUUM Article by Emily Linroth
Photography by Eric Schmitz
Lurking in leaf piles and crouching on logs is one of nature’s smallest superheroes. It prefers shade to the spotlight, and eats garbage with a vengeance. Behold: the mighty mushroom.
After centuries of trampling the most efficient recyclers nature has to offer, humans are finally beginning to see mushrooms as more than a gourmet meal. A new tactic in environmental cleanup known as mycoremediation uses fungi to transform environmental contaminants into harmless compounds.
"Humans seem very good at messing things up and throwing systems out of balance," said Erin Moore, a member of the Northwest Mushroomers’ Association. "Why not try to use tools like fungi to put them back into balance?"
Myco means "mushroom," and remediation is the process of restoring something to its optimal state. Mycoremediation is a part of mycorestoration, a term coined by mycologist (fungi researcher) Paul Stamets, to describe the use of fungi in aiding the environment.
That’s right. Mushrooms eat more than just rotting wood. Give them oil, arsenic or even nerve gas, and they’ll give you back water and carbon dioxide.
No, you’re not hallucinating. Mushrooms are nature’s prime decomposers, and they’re very good at what they do. They eat by releasing enzymes capable of breaking down substances from which they gain nutrients. Their usual diet consists of plants and other organic, or carbon-based, organisms.
Since many toxins have similar chemical makeup to plants, fungi can break them down as well. These include petroleum products, pesticides, fertilizers, pharmaceuticals with estrogen, and even neurotoxins. Once the contaminants are broken down, the mushrooms are safe to eat.
Mushrooms can also absorb heavy metals such as mercury, lead and arsenic. A species called oyster mushrooms, Pleurotus ostreatus, have a particularly high tolerance for areas heavily contaminated with cadmium and mercury. This means oyster mushrooms can grow in high-mercury areas and still decompose other pollutants.
Mushrooms that ingest heavy metals are no longer safe to eat, because the toxins remain concentrated in the mushroom instead of being broken down. For this reason, heavy-metal laden mushrooms must be removed after absorption to prevent the metals from reentering the area when the mushrooms die and decompose.
Oyster mushrooms gained national attention after the Nov. 7, 2007 Cosco Busan oil spill, when nearly 60,000 gallons of diesel fuel were dumped into San Francisco Bay. To test the potential of mycoremediation, workers mopped up oily beaches with mats of human hair, which is extremely absorbent. Oyster mushroom spores were introduced and began growing on the mats, decomposing the oil. The result: water, carbon dioxide, compost material suitable for highway landscaping and restored beaches.
Once the oyster mushrooms run out of food, they will die off and decompose naturally, posing no threat to the environment, according to the Environmental Protection Agency.
Mycoremediation was first attempted in Bellingham in 1998, when Stamets and a team of researchers from Battelle Pacific Northwest Laboratories in Sequim, Wash. treated plots in a contaminated truck maintenance yard operated by the Washington State Department of Transportation. Of the four plots, one received mushroom spores, two received bacterial treatments and one was left as a control. After four weeks, the plots not treated with spores remained unchanged, but the spore-rich plot had sprouted a large crop of oyster mushrooms. Over the next five weeks, the mushrooms matured, reproduced and then died. Their life cycle attracted insects, birds and other animals, and life flourished on the once-dead plot.
Mycorestoration was also used to filter contaminated water after Hurricane Katrina’s rampage through the Gulf Coast States in 2005, according to the National Institute of Environmental Health Sciences. Mushrooms are also capable of breaking down infectious agents such as E.coli and staphylococcus bacteria, according to Stamets’ book "Mycelium Running: How Mushrooms Can Help Save the World." Fungi have also been used at Superfund sites, some of the most toxic hazardous waste sites, throughout the nation.
Mycoremediation has potential for future expansion. Mushrooms could be used to break down pesticides released from Whatcom County farms before they reach rivers and the food chain. Fungi could take up heavy metals from the Georgia Pacific site, restoring the land more rapidly to pave way for Bellingham’s future waterfront development.
Mycoremediation has many benefits compared to traditional cleanup processes, according to the United States Geological Survey (USGS). Since mycoremediation can be carried out at the contaminated location, the site doesn’t need to be disrupted, preventing the release of more toxins. Also, mycoremediation is a completely natural process requiring minimal supervision, making it much cheaper than more institutionalized methods such as incineration.
The success of fungi is due to their nature and their structure, according to Dr. Fred Rhoades, a biology professor and avid mycologist at Western Washington University.
Fungi are different from plants because they cannot produce their own food. Because of this, many species work with plants or bacteria to break down other substances into nutrients, which they then absorb.
"It’s a fantastic relationship," said Moore. "These fungi actually grow on the very fine, absorbing tree roots, just like a glove on a hand."
The fungi carry nutrients and water to the trees, which feed sugars to the fungi.
Fungi also have a much different structure than plants. Although the mushroom itself is the most popular image we have of a fungus, it actually only makes up a small part of the organism.
The mushrooms we see are fruiting bodies – they produce spores, much like the fruiting parts of a plant produce seeds. Mushrooms are part of a larger organism known as the mycelium. All fungi are made up of mycelium, even those that do not form mushrooms.
"The mushroom is like the apple, and the mycelium is like the apple tree," Rhoades said.
Mycelia (plural of mycelium) are complex webs of hair-like fibers that resemble the neurological pathways in the human brain. Although only one cell wall thick, mycelia are responsible for cycling nutrients through the fungus and its surrounding environment, according to Stamets’ book.
Mycelium mats can grow very large and connect entire forests in a nutrient-sharing network. One specimen covered more than 2,400 acres on an Oregon mountaintop; possibly the largest living organism, according to the journal "Nature."
Some fungi will decompose anything that provides them with nutrients, Rhoades said, but others are picky eaters. Mycoremediation occurs most successfully when mycelia of local mushrooms are bred to target specific contaminants, according to Stamets’ book.
Since mycoremediation is an emerging field, plenty of testing must be done before it can be used on a wide scale, according to Stamets’ book.
Mushroom enthusiast Angus Tierney of Evergreen State College, Wash. believes mycoremediation would profit both the environment and the mushrooms themselves.
"All life on earth benefits from a toxin-free environment, including mushrooms," Tierney said. "If mushrooms were extensively used in this way, it could change many minds that correlate them with putrid rot and poison into seeing how mushrooms are healing."
Emily Linroth studies environmental science. She has been published in The Planet.
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