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  • Hiyam Jafar

Can Fungi Eat Pollution?!? + Other Secret Super Powers




Introduction:

Mycoremediation is a form of bioremediation in which fungi are used to decontaminate the environment from substances such as heavy metals, petroleum fuels, and other pollutants. This can occur in a number of ways: the contaminants may be absorbed passively into the mycelium of the fungi and then stored, or the secretion of extracellular enzymes can cause them to be broken down and the resulting compounds are then absorbed by the mycelium.


As pollution becomes an increasingly pressing issue, scientists continue to search for sustainable alternatives to day to day objects, while also searching for ways to combat this increase in pollution. One method that seems foolproof when it comes to the removal of many harmful pollutants is mycoremediation; fungi’s unique capability of decomposing such a wide range of substances seems to be the solution to removing heavy metals, organic pollutants, pharmaceutical products, dyes, and many others from the environment. In this article, we will explore the benefits and drawbacks of utilizing mycoremediation, as well as fungi’s effectivity when it comes to the absorption and breaking down of heavy metals and polycyclic aromatic hydrocarbons.



Heavy Metals and Mycoremediation:

Heavy metals are inorganic metals with relatively high densities or high atomic numbers. They include zinc and iron, which are essential nutrients, but also arsenic, mercury, lead and nickel, which are highly poisonous to animals and plants alike. These metals often make their way into the water or soil used for agriculture, which results in plants that are contaminated and can cause heavy metal poisoning when ingested. The symptoms of heavy metal poisoning are numerous and vary from one metal to another. Below is a list of possible symptoms that can be caused by different heavy metals.

  • Mercury poisoning: symptoms in adults include difficulties in hearing and speaking, lack of coordination, nerve loss in the hands/face, trouble walking, and vision changes, while in children it can cause a delay in cognition and speech development and lack of fine motor skills. Can result in death.

  • Lead poisoning: can cause developmental delay, learning difficulties, loss of appetite, irritability, hearing loss, and abdominal pain in children, and manifests as high blood pressure, headaches, muscle or joint pain, difficulties with memory or concentration, and mood disorders in adults.

  • Arsenic poisoning: causes abnormal heart rhythm, muscle cramps, red/swollen skin, abdominal pain, constant sore throat, and digestive issues, even death in extreme cases.

Fungi remove these heavy metals through biosorption; they are hyper-accumulated within their fruiting bodies, entering the mycelium passively and with little to no intracellular uptake. This means that the fungi, especially those that have been exposed to these heavy metals for a long period of time and have thus adapted to store them, are largely unaffected by their presence.


Fungi such as Pleurotus, Aspergillus, and Trichoderma can thus be planted in contaminated soil so that the heavy metals are removed and the soil can safely be used for agricultural purposes.



Organic Pollutants (Polycyclic Aromatic Hydrocarbons):

Polycyclic aromatic hydrocarbons (PAHs) are complex organic compounds with long-chain carbon bases that are found in coal, crude oil and gasoline. They are hydrophobic and very thermally stable, which makes them stubborn pollutants that are toxic to plants, animals and microorganisms. If highly exposed to them, they can cause blood and liver problems and even cancer in humans.


Fungi decompose PAHs through the secretion of the same extracellular enzymes that they use to break down wood, such as lignin peroxidase, versatile peroxidase, manganese peroxidase, general lipase and laccase. This proves highly effective because lignin and cellulose, the two primary plant fibers in wood, have a similar structure to PAHs. The similarities in their structures allow them to be broken down by the enzymes in the same way, and the resulting compounds are then absorbed into the mycelium. In this way, fungi can be used to clean oil spills.



Benefits and Drawbacks of Mycoremediation

Although mycoremediation may seem to be the perfect solution, the reality remains that it can be rather time-consuming for the fungi to establish their mycelium network and begin the process of cleaning up the environment they were planted in. Additionally, it cannot always be guaranteed that the fungi will even grow; a native species must be matched to the polluted environment.


So, despite the process being inexpensive and highly energy efficient, further studies are required in order for mycoremediation to be utilized on a larger, more global scale. While some of the results from small-scale experiments and tests carried out on fungi growing in polluted mediums often yield promising results, they are inconclusive, and many more tests and experiments need to be conducted in order to obtain a deeper understanding of the fungi themselves so that mycoremediation can become a universal solution rather than a hypothetical one.



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