Fungi Superheroes: Cleaning Polluted Water, Saving The Planet

Fungi are an incredibly diverse group of organisms, with an estimated 2 million species, and they could be the answer to cleaning up polluted water. Mycofiltration, or mycoremediation, is an eco-friendly technology that involves passing contaminated water through a network of fungal mycelium. This process has gained momentum as a potential solution to the problem of water pollution, which affects countries like Mexico, where 59.1% of surface water is contaminated. Fungi have a variety of enzymes that can break down a wide range of chemicals, including polyaromatic hydrocarbons, heavy metals, herbicides, pesticides, cyanotoxins, pharmaceuticals, and antibiotics. They can also transform dissolved forms of certain elements into solid biominerals, which is useful for water treatment. For example, some common soil fungi can transform dissolved selenium, a contaminant often released by coal mining, into solid selenium, which can then be collected and reused. This process could offer a low-cost, low-input alternative for environmental clean-up applications.

Mycofiltration

Fungi are well-known for their ability to break down organic matter and tolerate extreme conditions, making them ideal candidates for cleaning up polluted environments. Mycofiltration involves the use of specific fungi species that have a unique capacity to filter and remove contaminants from water. These fungal species can be employed in a variety of ways to treat polluted water, including through the use of fungal mycelium, which acts as a natural filter.

One of the most well-studied and effective fungi for mycofiltration is Trametes versicolor, also known as the turkey tail fungus. This fungus is renowned for its ability to

Selenium removal

Selenium (Se) is an essential trace element for most life forms. However, elevated levels of selenium generated by anthropogenic activities can be harmful to animals. Fungi have been found to play a crucial role in selenium removal from contaminated water.

In a study published in the journal Environmental Science & Technology, researchers from the University of Minnesota investigated the response of common soil fungi to selenium as a pollutant. They discovered that the fungi transformed dissolved selenium into solid biominerals, specifically manganese oxide and elemental selenium biominerals. This process indicates the existence of a previously unknown cryptic selenium cycle in nature.

Further research has focused on identifying specific fungal species capable of selenium removal. Bench-scale pure-culture experiments have been conducted with Se-reducing fungal isolates, including Alternaria alternata strain SRC1lrK2f and Alternaria sp. strain CMED5rs1aP4. These isolates were chosen due to their ability to remove selenium from synthetic growth media and their presence in natural environments exposed to selenium pollution, such as coal mine drainage treatment systems and reclaimed mining sites.

Supplemental carbohydrate- or glycerin-based carbon products have been used in wastewater experiments to enhance fungal growth and selenium removal. These supplements have been found to promote Se removal from municipal wastewater but have minimal impact on industrial wastewater removal. The use of fungi for selenium bioremediation offers a low-cost, nature-based solution to complement traditional water treatment methods, especially in places like Mexico, where water pollution is a significant environmental concern.

Overall, fungi show great potential for the mycoremediation of selenium-contaminated wastewaters, providing an alternative direction for biorecovery and ensuring that the water is of better quality.

Mycoremediation

Fungi have several advantages as a remediation method. They are hyperaccumulators, meaning they can concentrate toxins in their fruiting bodies for later removal. They can also produce valuable byproducts such as enzymes, edible or medicinal mushrooms, and biominerals. For example, certain species of fungi can absorb and retain radionuclides, and their cell walls can be used as filters to adsorb heavy metals and radionuclides, preventing their release into the environment. Additionally, some mycoremediators train their mushroom strains to eat specific contaminants, and certain species of mushrooms are more effective at remediating certain contaminants.

When cultivating mushrooms for mycoremediation, it is important to understand basic mycology and know how to cultivate and care for mushrooms. Mushrooms and mycoremediation installations require moisture, shade, air, and the right temperature to grow. Different species of mushrooms have different temperature ranges and substrate preferences. For example, some grow best in logs, while others prefer wood chips, cardboard, corn cobs, or cotton rags. It is also important to use fresh wood chips (between 2 weeks and 2 months old) to avoid competitor fungal species. Hardwoods are preferred, and anti-fungal species like cedar should be avoided.

Biomineral formation

Fungi are adept at facilitating biomineral formation, a process that holds promise for water purification. This occurs through the precipitation of minerals from aqueous solutions, which can effectively sequester pollutants. The following paragraphs delve into the intricacies of this phenomenon.

Fungi exhibit remarkable capabilities in inducing and regulating the formation of biominerals, particularly through the process of biomineralization. This involves the controlled precipitation of minerals from their surrounding environment, often resulting in the creation of intricate and functional structures. The participation of fungi in biomineral formation is a dynamic and complex process that is influenced by various factors, including the specific fungal species, the composition of the growth media, and environmental conditions.

Mechanisms of Biomineral Formation

Fungi employ diverse mechanisms to induce biomineral formation. One prominent mechanism involves the production of organic acids, such as oxalic, citric, and gluconic acids, which can dissolve minerals and metal ions from the substrate. These dissolved ions can then precipitate, forming biominerals. Fungi also secrete a range of biosurfactants and extracellular polymeric substances (EPS) that play critical roles in biomineral formation. Biosurfactants reduce the surface tension, promoting the dispersal of ions and the formation of mineral nanoparticles. Meanwhile, EPS provides a structural framework for the nucleation and growth of biominerals, influencing their size, shape, and composition.

Factors Influencing Biomineral Formation

The composition of the growth media is crucial for biomineral formation. Ions such as calcium, iron, and manganese can influence the type and extent of biomineralization. Additionally, environmental conditions like pH, temperature, and oxygen levels, dictate the rate and nature of biomineral formation. Optimal conditions facilitate the precipitation of desired minerals, while suboptimal conditions may hinder the process or lead to the formation of less functional biomineral structures.

Applications in Water Purification

The ability of fungi to induce biomineral formation has potential applications in water purification. By promoting the precipitation of pollutants as biominerals, fungi can remove contaminants from water. For instance, certain fungal species facilitate the biomineralization of heavy metals like lead, cadmium, and mercury, rendering them insoluble for easy disposal. This natural process offers a sustainable approach to water pollution treatment, harnessing fungi's power to restore aquatic ecosystems and protect public health.

Environmental clean-up applications

Fungi have been identified as a potential solution for cleaning up polluted water. This process is known as mycofiltration or mycoremediation and involves passing contaminated water through a network of fungal mycelium. Mycofiltration is an environmentally friendly technology that has gained momentum in recent years, with research focusing on the types and levels of contaminants removed.

Fungi have a wide variety of enzymes that enable them to break down chemicals and extract energy and molecules to nourish themselves. They can break down contaminants such as polyaromatic hydrocarbons (found in crude oil and gasoline), heavy metals, herbicides, pesticides, cyanotoxins, pharmaceuticals, antibiotics, phthalates, dyes, and detergents.

Scientists have discovered that certain species of fungi, such as those from the Alternaria genus, can transform selenium from its dissolved form to a solid form in the presence of oxygen. This is particularly useful for treating water contaminated by coal mining and processing, which release high levels of selenium into the environment. In a laboratory setting, scientists have successfully tested the use of Alternaria fungi to remove selenium from wastewater, with promising results.

Fungi-based water treatment offers a low-cost, low-input, and sustainable solution for a wide variety of environmental clean-up applications. The simplicity and sustainability of biotechnological treatments, combined with the ease of preserving and feeding fungi, make them an attractive option for combating water pollution.

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