Mycoremediation (mykes, “fungus” and remedium, “a cure”) is a technique that utilizes the vegetative portion of a fungus to remove contaminants from a substrate—usually soil.
Scientists have discovered several ways in which fungi “decontaminate” their surroundings. These biological processes have been taking place for millennia; it is only recently that scientists have learned how fungal organisms remove or neutralize a myriad of substances—many of them toxic—from polluted sites.
As a fungus extends through its environment, its root-like hyphal cells form a network called a “mycelium.” This often invisible mat may extend over thousands of acres, while fungal fruiting bodies—mushrooms being the most familiar ones—may only appear in small clusters or as single specimens. Some fungi don’t form visible fruiting bodies at all; they may remain out of sight as symbiotic organisms on the roots of plants.
Fungi and Hydrocarbons
A fungal mycelium excretes digestive enzymes as it grows. These enzymes break down surrounding organic matter which is then absorbed into the fungal cells for nutrition. Since the molecules found in hydrocarbons (oil and petrochemicals) are the same as those found in carbohydrates (plant-based material), many fungi possess the ability to break down both.
Researchers at Batelle Memorial Institute are developing patented strains of fungi with enhanced capabilities based upon the fungi’s native biochemistries. Investigations reveal that a fungus can be conditioned to deal with a specific contaminant, such as aromatic hydrocarbons or chlorinated compounds. (Fungal Development)
Fungi and Pesticides
Pesticide residues in soils represent one of agriculture's most vexing environmental problems. These contaminants--some of which are known carcinogens--often find their way into waterways and aquifers.
Researchers in Britain have demonstrated that inoculating contaminated soils with fungi enhances the degradation of multiple chemicals, such as simazine, trifluralin and dieldrin. This beneficial activity occurs even at levels of soil hydration that would be hostile to plants. (Fragoeiro S, Magan N. Impact of Trametes versicolor and Phanerochaete chrysosporium on differential breakdown of pesticide mixtures in soil microcosms at two water potentials and associated respiration and enzyme activity. International Biodeterioration & Biodegradation 2008;62(4):376-383)
Fungi and Metals
Scientists at the University of Dundee in Scotland have discovered that mycorrhizal fungi can sequester uranium (from spent ammunition) discarded on battlefields. Dr Geoffrey Gadd, one of the study's principal investigators, has also shown that fungi are intimately involved in recycling several other metals, including cadmium and selenium. (Gadd G. Mycotransformation of organic and inorganic substrates. Mycologist 2004;18:60-70)
Thus, by employing fungal technologies, previously unusable battlefields and contaminated industrial sites may potentially be reclaimed.
Fungi and Watershed Protection
In his 1993 book, Growing Gourmet & Medicinal Mushrooms, Paul Stamets eloquently explained the concept of mycofiltration, a process whereby the mycelium of a fungus can be utilized to protect watersheds from contamination by nearby sites. In essence, a fungal mycelium can be established near a polluted area, and the network of cells will filter harmful microbes, chemicals, and even some heavy metals from the effluent leaving the contaminated site.
As clean water becomes scarcer and, unfortunately, environmental contamination becomes more commonplace, fungi may play vital roles in protecting this precious resource.
Though the concept of mycoremediation is in its infancy, this evolving technology holds great promise. Fungi can be introduced into a contaminated environment relatively cheaply. Once their work is completed, cleanup will be vastly simplified, because fungal metabolism leaves residues that are either harmless or significantly less toxic than the original substrate.
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