Something Under the Soil
Green Mountain College students are well informed about how their daily actions impact the environment. The use of gas powered cars not only emit toxins, but also require a network of systems that ensure the availability of gasoline. Petroleum, the basis of gasoline is transported by oceanic tankers and transcontinental pipelines that frequently spill. The food that we eat comes from agriculture, and the growing of crops like corn require the use of pesticides and nutrients. These chemicals help crops grow but also seep into waterways and destabilize ecosystems resulting in sickness and even death. Beyond the stories of gasoline and food, Green Mountain College students are aware of the many ways that their daily actions impact the environment. Since we are well informed about these disturbing impacts of our actions, it seems appropriate to tell a story of hope.
Interestingly enough, this story begins in the Old Growth Forests of the Pacific Northwest where an immense variety of mushroom species grow, including the world’s largest organism, the honey fungus (Armillaria ostoyae). This fungus’ underground root-like system, referred to as a mycelial network, spans an area of 3.7 square miles along the slopes of Oregon’s Blue Mountains and is thought to be somewhere between 1,900 and 8,650 years old. The discovery of the honey fungus’ mycelial network rekindled a heated debate amongst biologists as to what defines an individual organism. Since the honey fungus had genetically identical cells that could communicate and coordinate, biologists concluded that the honey fungus’ mycelial network was indeed an individual organism. Although these giant fungi were not discovered until the late 1990’s, Biochemist Myron Smith of Carleton University in Ottawa, Ontario believes that they are “not very rare” and “in fact normal” (Casselman).
Like the vast mycelial networks of the honey fungus, there are many properties of fungi that still lie below the surface. Paul Stamets, a prominent mycologist who studied at Evergreen State College in Olympia, Washington has published substantial research on the use of fungi to repair human-degraded environments. Stamets calls this process mycorestoration, myco- referring to fungi, and restoration- referring to healing. In his book Mycelium Running, Stamets describes restorative applications of fungi including mycofiltration, mycopesticides and mycoremediation.
Mycofiltration is the use of mycelium as a membrane for filtering out microorganisms, pollutants and silt from water (Stamets 55). A mycelium can be used to filter silt, chemical toxins like pesticides and nutrients, and pathogens such as bacteria and viruses. This filtration is a result of the density of microscopic hyphae cells within mycelial masses. In fact, “More than a mile of threadlike mycelial cells can infuse a gram of soil” (Stamets 55). These vast networks of hyphae are first inoculated on a substrate such as a bale of straw and then introduced into polluted waterways. As the fungus enters the water it acts as a cellular net, catching and consuming parasites, debris, or nutrients from agricultural runoff. Varying fungal species have unique appetites and can be selected to target specific pollutants. For example, strains of the zhu ling mushroom (Polyporus umbellatus) can successfully filter the malarial parasite, Plasmodium falciparum, through the inoculation of a submerged substrate (Lovy et. all). Mycofiltration could be implemented in variety of scenarios including third-world water sources to promote hygiene, disease control, and the availability of safe drinking water. Fungi could also be used to filter pollutants from farm, factory, and residential runoff.
Paul Stamets’ second use of fungi to remediate environments is called mycopesticides. Chemical pesticides used in houses and farms pose major threats ecosystems and water sources. Toxic chemicals such as organophosphates are commonly sprayed onto crops to kill pests. The problem with spraying pesticides is that they come into contact with many other organisms other than their target species. Through the process of bioaccumulation, toxins in pesticides accumulate in, and often kill, apex predators. One example of this phenomenon were the effects of DDT on bald eagles in the mid 20th century. As a alternate to organophosphates, mycopesticides are parasitic fungi that target specific pests, and do not harm humans (Stamets 115). In attempt to avoid ecological harm, Paul Stamets has been experimenting with mycopesticides in his own home in Washington state. Stamets introduced the fungus, Metarhizium anisopliae, into an ant colony (Camponotus spp.) that infested his house by feeding the them inoculated rice. Days later the fungi eradicated the infected ants by fruiting inside their stomachs. The ants that were not initially infected soon became so when spores were released into the midst of the household colony by the mushrooms growing on the ant corpses. “A couple of weeks later, my old, decomposing farmhouse was free of carpenter ants and was never reinvaded,” reports Stamets as he reflects on his household experiment (115). Research by Stamets and at the Texas A&M university continue to suggest mycopesticides could be an environmentally friendly alternative to chemical pest control, although, could mycopesticides become invasives? Perhaps local species of fungi could be used as mycopesticides to avoid that potential problem.
Paul Stamets’ third use of fungi to restore damaged environments is called mycoremediation. This process uses fungi and their digestive enzymes to decompose a variety of toxins in terrestrial environments. Many fungi species that consume wood are also capable of eating petroleum products such as diesel, plastics and many herbicides and pesticides (Stamets 88). This is because the bonds that hold together the hydrocarbon chains of petroleum products are similar to those of lignin and cellulose. White rot mushrooms such as the oyster mushroom (Pleurotus ostreatus) are some of the most capable of breaking down these toxins. This is because the white rot mushrooms secrete peroxidases and laccases in their digestive enzymes. In the Washington State Department of Transportation Diesel Contaminated Maintenance Yard Experiment, Stamets used oyster mushrooms to inoculate a pile of diesel fuel-saturated wood chips. The mushrooms successfully consumed and eliminated the toxic chemicals from the diesel to the extent that plants began to grow in the remnants of the experiment (Stamets 93). Fungi have been used to decompose anthracenes, anthraquinones, benzopyrenes, chlorinated aromatic compounds, copper/chromium, dimethyl methylphosphonates (DMMP), dioxins, pentachlorophenols, pesticides, and petroleum hydrocarbons (Stamets 95). Although mycoremediation may not eliminate every toxic particle in a given substrate, fungi’s capacity to breakdown these toxins is a major discovery. Perhaps ecological succession could continue to remediate damaged environments after the implementation of white rot fungi. Mycorestoration including: mycofiltration, mycopesticides, and mycoremediation have remarkable implications for stabilizing the biosphere and reducing human impacts. Paul Stamets is convincing that mushrooms can save the world.
Work Cited
Casselman, Anne. “Strange but True: The Largest Organism on Earth Is a Fungus.” Scientific American, 4 Oct. 2007, www.scientificamerican.com/article/strange -but-true-largest-organism-is-fungus/.
Lovy, A., B. Knowles, R. Labbe, and L. Nolan. 1999. Plasmodium falciparum. Journal of Herbs, Spices & Medicinal plants. 6(4): 49-57.
"Pacific Indoor Air Quality." Zygomycetes. Http://pacificiaq.com/, n.d. Web. 17 Apr. 2015.
Stamets, Paul. "Part II." Mycelium Running: How Mushrooms Can Help save the World. Berkeley, CA: Ten Speed, 2005. 55-123. Print.