Mycoremediation

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Mycoremediation is a form of bioremediation, the process of using fungi to degrade or sequester contaminants in the environment. Stimulating microbial and enzyme activity, mycelium reduces toxins in-situ. Some fungi are hyperaccumulators, capable of absorbing and concentrating heavy metals in the mushroom fruit bodies.

One of the primary roles of fungi in the ecosystem is decomposition, which is performed by the mycelium. The mycelium secretes extracellular enzymes and acids that break down lignin and cellulose, the two main building blocks of plant fiber. These are organic compounds composed of long chains of carbon and hydrogen, structurally similar to many organic pollutants.[1] The key to mycoremediation is determining the right fungal species to target a specific pollutant. Certain strains have been reported to successfully degrade the nerve gases VX and sarin.[2]

There are many factors that affect the rate and ability for mushrooms to break down toxins, the first of which is the physical nature of the hydrocarbons. Generally, contaminants that are molecularly simpler are easier to break down than more complicated ones. Temperature also controls the rate at which contaminants are broken down. Low temperatures slow the process and warm temperatures speed it up. Fungi prefer a pH of 4 to 5, that is they prefer a pH which is slightly more acid than a neutral pH which is 7. Oxygen is also essential to fungal metabolism. The initial step of hydrocarbon degrading involves adding oxygen to the hydrocarbon, and so a lack of oxygen in the environment slows the process.[3][page needed]

Oyster mushrooms (Pleurotus ostreatus)

In an experiment conducted in conjunction with Dr. S. A. Thomas, a major contributor in the bioremediation industry, a plot of soil contaminated with diesel was inoculated with mycelia of oyster mushrooms; traditional bioremediation techniques (bacteria) were used on control plots. After four weeks, more than 95% of many of the PAH (polycyclic aromatic hydrocarbons) had been reduced to non-toxic components in the mycelial-inoculated plots. It appears that the natural microbial community participates with the fungi to break down contaminants, eventually into carbon dioxide and water. Wood-decay fungi are particularly effective in breaking down aromatic pollutants (toxic components of petroleum), as well as chlorinated compounds (certain persistent pesticides).[4]

In 2007 a similar method was used in San Francisco. Oil had contaminated the shoreline after a cargo ship spilled 58,000 gallons of heavy fuel oil. Hair mats, the size of a doormat, acted as sponges to soak up spilled oil. An experiment was designed at the Presidio of San Francisco with hair mats, oil, oyster mushroom, and straw. However, the mushrooms did not break down the oil but instead died most likely due to the high viscosity and toxicity of the heavy bunker oil and the design of the experimental bins.[5]

The concept of mycoremediation was explored in the 1984 film Nausicaä of the Valley of the Wind, where vast tracts of fungal forest rehabilitate the planet after catastrophic human polluting and apocalypse.

Mycofiltration is a similar process, using fungal mycelia to filter toxic waste and microorganisms from water in soil.

According to Paul Stamets, the future of mycoremediation lies in Mycological Response Teams. These teams would consist of knowledgeable and trained people who would set up centers that would use mycoremediation techniques to recycle and rebuild healthy soil in the area. This begins by spreading awareness and information in regards to the benefits of mycoremediation.[6]

See also[edit]

References[edit]

  1. ^ Stamets, Paul. undated. "Helping the Ecosystem through Mushroom Cultivation." Adapted from Stamets, P. 1998. "Earth's Natural Internet." Whole Earth Magazine, Fall 1999.
  2. ^ Stamets, Paul (2004). "Magic Mushrooms: Planetary Healing with Deep Biology". In Kenny Ausubel & J.P. Harpignies. Nature's Operating Instructions: The True Biotechnologies (in English). San Francisco: Sierra Club Books. p. 39. ISBN 1578050995. 
  3. ^ Singh, Harbhajan (2006). Mycoremediation: fungal bioremediation. New York: Wiley-Interscience. ISBN 0-471-75501-X. 
  4. ^ Thomas, S.A. 2000. "Mushrooms: Higher Macrofungi to Clean Up the Environment", Battelle Environmental Issues, Fall 2000
  5. ^ May, Meredith (14 November 2007). "Hair and mushrooms create a recipe for cleaning up oily beaches". San Francisco Chronicle. Retrieved 8 May 2013. 
  6. ^ "The Petroleum Problem". Fungi Perfecti. 3 June 2010. Retrieved 8 May 2013. 

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