Treatment of wastes, effluents and contaminated media in Environment and other scientific fields is a fast-growing field of technology today. The prime reason behind this is the rising levels of pollution and environmental degradation.

Scientists have developed numerous physical, chemical, biological and biogeochemical methods for the effective treatment of contaminated resources and media to revive their quality and make them fit for intensive use again.

Scientists have been looking for cheap and efficient remediation methods. Some of the methods like Electroremediation are very expensive and require specialized equipment. One of the most popular and cost-effective methods among them is Bioremediation.

Bioremediation

Bioremediation is a process used to treat contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate the growth of microorganisms and degrade the target pollutants.

 It is less expensive and more sustainable than other physical and chemical remediation alternatives. Biological treatment is a similar approach used to treat wastes including wastewater, industrial waste, and solid waste.

Bioremediation using Fungi

Biological approaches based on industrial and environmental biotechnology is focusing on the development of “clean technologies” which emphasizes on the maximum production, reduced waste generation, treatment and conversion of waste in some useful form.

One such biological method is Mycoremediation which is based on the use of various forms of fungi for the removal of waste from the environment.

Mycoremediation

Bioremediation using Fungi

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. Mycoremediation is a form of bioremediation in which fungi-based technology is used to decontaminate the environment.

 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 in the land, sweet water, and marine environments.

Types of treatment

Fungi use different methods to decontaminate polluted spots and stimulate the environment. These methods include

  • Biodegradation
It is the ultimate degradation and recycling of complex molecule to its mineral constituents. It is the process which leads to complete mineralization of the starting compound to simpler ones like CO2, H2O, NO3 and other inorganic compounds by living organisms, especially microbes.
  • Biosorption
The process of removal of metals/pollutants from the environment by fungi is biosorption. Biosorption is considered as an alternative to the remediation of industrial effluents as well as the recovery of metals present in the effluent.
 
Biosorption is a process based on the sorption of metallic ions/pollutants/xenobiotics from effluent by live or dried biomass which often exhibits a marked tolerance towards metals and other adverse conditions.
  • Bioconversion

The conversion of industrial or agro-industrial sludges into some other useful forms is called Bioconversion.

Contaminants/Pollutants 

Mycoremediation is being popularly used around the world by scientists and waste treatment experts for removal of contaminants and pollutants like:

  • Metals
A variety of fungi, such as Pleurotus, Aspergillus, Trichoderma has proven to be effective in the removal of lead, cadmium, nickel, chromium, mercury, arsenic, copper, boron, iron and zinc in the marine environment, wastewater and on land.
  • Organic pollutants
Fungi are very efficient in the decomposition of matter. Wood-decay fungi, especially white rot, secrete extracellular enzymes and acids that break down lignin and cellulose, the two main building blocks of plant fiber. 
  • Pesticides
Pesticide contamination can be long-term 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.
  • Dyes
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 and Congo red.

Benefits of Mycoremediation

The byproducts of the remediation can be valuable materials themselves, such as enzymes like laccase, edible or medicinal mushrooms, making the remediation process even profitable.

 Fungi, with the help of their non-specific enzymes, are able to break down many kinds of substances. They are used for

  • Pharmaceuticals and fragrances that normally are recalcitrant to bacteria degradation, such as paracetamol, the breakdown products of which are toxic
  • Traditional water treatment, using Mucor hiemalis, and the phenols and pigments of wine distillery wastewater.
Mycoremediation is one of the cheaper solutions to remediation, and it doesn’t usually require expensive equipment. For this reason, it is often used also in small-scale applications, such as Mycofiltration of domestic wastewater, and to help with the decomposition process of a compost toilet.

Synergy with Phytoremediation – Mycorrhiza

Phytoremediation refers to the technologies that use living plants to clean up soil, air, and water contaminated with hazardous contaminants. It is defined as “the use of green plants and the associated microorganisms, along with proper soil amendments and agronomic techniques to either contain, remove or render toxic environmental contaminants harmless”.

 Phytoremediation is a cost-effective plant-based approach to remediation that takes advantage of the ability of plants to concentrate elements and compounds from the environment and to metabolize various molecules in their tissues. 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.

This relationship has been proven useful with many pollutants, such as:

  • Rhizophagus intraradices and Robinia pseudoacacia in lead-contaminated soil.
  • Rhizophagus intraradices with Glomus versiforme inoculated into vetiver grass for lead removal.
  •  AMF and Calendula officinalis in Cadmium and lead-contaminated soil.

This remediation method, in general, was effective in increasing the plant bioremediation capacity for metals, petroleum fuels, and PAHs. AMF greatly promote the biodegradation of organic pollutants in wetlands like benzene-, methyl tert-butyl ether- and ammonia from groundwater when inoculated into Phragmites australis.