Question: How was Mycoremediation discovered?

Mycoremediation

Mycoremediation (from ancient Greek μύκης (mukēs), meaning "fungus" and the suffix -remedium, in Latin meaning 'restoring balance') is a form of bioremediation in which fungi-based technology is used to decontaminate the environment. Fungi have been proven to be a very cheap, effective and environmentally sound way for helping to remove a wide array of toxins from damaged environments or wastewater. The toxins include heavy metals, persistent organic pollutants, textile dyes, leather tanning industry chemicals and wastewater, petroleum fuels, polycyclic aromatic hydrocarbon, pharmaceuticals and personal care products, pesticides and herbicide,[1] in land, fresh water and marine environments. 
The byproducts of the remediation can be valuable materials themselves, such as enzymes (like laccase[2]), edible or medicinal mushrooms,[3] making the remediation process even profitable.
Pollutants

Fungi, thanks to their non-specific enzymes, are able to break down many kinds of substances. They are used for pharmaceuticals and fragrances that normally are recalcitant to bacteria degradation,[4] such as paracetamol, the breakdown products of which are toxic in traditional water treatment, using Mucor hiemalis,[5] but also the phenols and pigments of wine distillery wastewater,[6] X-ray contrast agents and ingredients of personal care products.[7]
Mycoremediation is one of the cheaper solutions to remediation, and it doesn't usually require expensive equipment. For this reasons it is often used also in small scale applications, such as mycofiltration of domestic wastewater,[8] and to help with the decomposition process of a compost toilet.
Metals
Pollution from metals is very common, as they are used in many industrial processes such as electroplating, textiles,[9] paint and leather. The wastewater from these industries is often used for agricultural purposes, so besides the immediate damage to the ecosystem it is spilled into, the metals can enter far away creatures and humans through the food chain. Mycoremediation is one of the cheapest, most effective and environmental-friendly solutions to this problem.[10]
Many fungi are hyperaccumulators, that means they are able to concentrate toxins in their fruiting bodies for later removal. This is usually true for populations that have been exposed to contaminants for long time, and have developed a high tolerance, and happens via biosorption on the cellular surface, which means that the metals enter the mycelium in a passive way with very little intracellular uptake.[11]
A variety of fungi, such as Pleurotus, Aspergillus, Trichoderma has proven to be effective in the removal of lead,[12][13] cadmium,[14] nickel,[15][16] chromium,[17] mercury,[18] arsenic,[19] copper,[20][21] boron,[22] iron and zinc[23]  in marine environment, wastewater and on land.
Not all the individuals of a species are effective in the same way in the accumulation of toxins. The single individuals are usually selected from an old-time polluted environment, such as sludge or wastewater, where they had time to adapt to the circumstances, and the selection is carried on in the laboratory. A dilution of the water can drastically improve the ability of biosorption of the fungi.[24]
The capacity of certain fungi to extract metals from the ground also can be useful for bioindicator purposes, and can be a problem when the mushroom is an edible one. For example, the shaggy ink cap (Coprinus comatus), a common edible north-hemisphere mushroom, can be a very good bioindicator of mercury, and accumulate it in its body, which can also be toxic to the consumer.[25]
The capacity of metals uptake of mushroom has also been used to recover precious metals from medium. VTT Technical Research Centre of Finland reported an 80% recovery of gold from electronic waste using mycofiltration techniques.[26]
Organic pollutants
Fungi are amongst the primary saprotrophic organisms in an ecosystem, as they are efficient in the decomposition of matter.
Wood-decay fungi, especially white rot, secretes extracellular enzymes and acids that break down lignin and cellulose, the two main building blocks of plant fiber. These are long-chain organic (carbon-based) compounds, structurally similar to many organic pollutants. 
They do so using a wide array of enzymes. In the case of polycyclic aromatic hydrocarbons (PAHs), complex organic compounds with fused, highly stable, polycyclic aromatic rings, fungi are very effective[27] also in marine environments.[28] The enzymes involved in this degradation are ligninolytic and include lignin peroxidase, versatile peroxidase, manganese peroxidase, general lipase, laccase and sometimes intracellular enzymes, especially the cytochrome P450.[29][30]
Other toxins fungi are able to degrade into harmless compounds include petroleum fuels,[31] phenols in wastewater,[32] polychlorinated biphenyl (PCB) in contaminated soils using Pleurotus ostreatus,[33] polyurethane in aerobic and anaerobic conditions such as found at the bottom of landfills using two species of the Ecuadorian fungus Pestalotiopsis,[34] and more.[35]
The mechanisms of degradation are not always clear,[36] as the mushroom may be a precursor to subsequent microbial activity rather than individually effective in the removal of pollutants.[37]
Pesticides
Pesticide contamination can be long-term and have a significant impact on decomposition processes and thus nutrient cycling[38] and their degradation can be expensive and difficult.
The most used fungi for helping in the degradation of such substances are white rot ones which, thanks to their extracellular ligninolytic enzymes like laccase and manganese peroxidase, are able to degrade high quantity of such components. Examples includes the insecticide endosulfan,[39] imazalil, thiophanate methyl, ortho-phenylphenol, diphenylamine, chlorpyrifos[40] in wastewater, and atrazine in clay-loamy soils.[41]
Dyes
Dyes are used in many industries, like paper printing or textile. They are often recalcitant to degradation and in some cases, like some azo dyes, cancerogenic or otherwise toxic.
The mechanism the fungi degrade this dyes is their lignolytic enzymes, especially laccase, so white rot mushrooms are the most commonly used.
Mycoremediation has proven to be a cheap and effective remediation technology for dyes such as malachite green, nigrosin and basic fuchsin with Aspergillus niger and Phanerochaete chrysosporium[42] and Congo red, a carcinogenic dye recalcitrant to biodegradative processes,[43] direct blue 14 (using Pleurotus).[44]
Synergy with phytoremediation
Phytoremediation is the use of plant-based technologies to decontamination an area. Most of the plants can form a symbiosis with fungi, from which both the organisms get an advantage. This relationship is called mycorrhiza.
Mycorrhizal fungi, especially arbuscular mycorrhizal fungi (AMF), can greatly improve the phytoremediation capacity of some plants. This is mostly because the stress the plants suffer because of the pollutants is greatly reduced in presence of AMF, so they can grow more and produce more biomass.[45] The fungi also provide more nutrition, especially phosphorus, and promotes the overall health of the plant. The mycelium quick expansion also can greatly extend the rhizosphere influenze zone (hyphosphere), providing the plant with access to more nutrients and contaminants.[46] Increasing the rhizosphere overall health also means a rise in the bacteria population, which can also contribute to the bioremediation process.[47]
This relationship has been proven useful with many pollutants, such as Rhizophagus intraradices and Robinia pseudoacacia in lead contaminated soil,[48] Rhizophagus intraradices with Glomus versiforme incoulated into vetiver grass for lead removal,[49] AMF and Calendula officinalis in cadmium and lead contaminated soil,[50] and in general was effective in increasing the plant bioremediation capacity for metals,[51][52] petroleum fuels,[53][54] and PAHs.[55] In wetlands AMF greatly promote the biodegradation of organic pollutants like benzene-, methyl tert-butyl ether- and ammonia from groundwater when inoculated into Phragmites australis.[56]
See also
Biodegradation
Bioremediation
Compost
Mycorrhizal bioremediation
Phytoremediation
Paul Stamets