Degraded soils and fungi: pilot regeneration projects in Italy

This article explores in depth how these extraordinary life forms are revolutionizing our approach to environmental recovery, offering sustainable and economically advantageous solutions to restore vitality to compromised land.

Degraded soils: a national problem

Before delving into the solutions offered by the fungal kingdom, it is essential to understand the extent of the soil degradation problem in Italy. According to data from ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale - Higher Institute for Environmental Protection and Research), approximately 4.3% of the national territory shows significant levels of contamination, with peaks reaching 10-15% in some highly industrialized regions such as Lombardy, Piedmont, and Campania. The main contaminants include heavy metals (lead, cadmium, mercury), polycyclic aromatic hydrocarbons, chlorinated solvents, and persistent pesticides. This contamination represents not only a risk to the ecosystem but also to human health, through the food chain and the inhalation of contaminated dust.

Bioremediation with fungi: the scientific principles

Bioremediation, or biorisanamento, is a technology that uses living organisms to degrade, transform, or remove contaminants from the environment. Fungi, particularly wood-decaying (lignicolous) ones, possess extraordinarily powerful enzymes capable of breaking down complex and persistent molecules. The secret of this ability lies in their enzymatic apparatus, which includes laccases, manganese peroxidases, and lignin peroxidases—enzymes capable of oxidizing a wide range of recalcitrant organic compounds. These same enzymes, evolved to decompose lignin and cellulose in wood, can be effectively employed to degrade structurally similar pollutant molecules.

Mechanisms of fungal action in remediation

Fungi act through several simultaneous mechanisms that make them particularly effective in bioremediation:

Biodegradation

Fungi secrete extracellular enzymes that catalyze the breaking of chemical bonds in contaminant molecules, transforming them into less toxic or non-toxic compounds. This process is particularly effective against polycyclic aromatic hydrocarbons, chlorinated pesticides, and explosives.

Bioaccumulation and Hyperaccumulation

Some fungal species have the ability to absorb and concentrate heavy metals and other inorganic substances in their tissues, physically removing them from the soil. This process, known as phytoextraction when it occurs in plants, becomes mycoextraction when mediated by fungi.

Biotransformation

Some contaminants are not completely degraded but are transformed into less mobile, less toxic, or more easily degradable forms by other microorganisms. This process reduces the bioavailability and thus the toxicity of the contaminants.

Stimulation of the microbial community

The fungal mycelium creates a network that acts as a "biological highway" for bacteria and other microorganisms, facilitating their movement and metabolic interactions. Furthermore, fungi provide nutrients and favorable conditions for the development of degradative microbial communities.

Pilot soil regeneration projects with fungi in Italy

Italy is at the forefront of research and application of bioremediation techniques based on fungi. Several pilot projects, often born from collaboration between universities, research centers, and innovative companies, are successfully testing these technologies in real contamination scenarios.

The "Fungi Factory" project in Piedmont

In a former industrial area of Turin, a consortium led by the University of Turin started the "Fungi Factory" project in 2019, aimed at remediating soils contaminated with hydrocarbons and heavy metals through the combined use of fungi and plants. The project used native fungal species isolated from contaminated sites in the region, selected for their resistance and degradative capabilities. The results, after two years of treatment, showed a 78% reduction in total petroleum hydrocarbons and a 45% decrease in the concentration of lead and cadmium in the soil. This approach demonstrated an effectiveness 30% higher than traditional bioremediation techniques based solely on bacteria.

To learn more about bioremediation techniques based on fungi, the ISPRA website offers numerous scientific publications and operational guidelines.

Mycoremediation in Sicily: the case of illegal landfills

In Sicily, where the problem of illegal landfills has reached alarming proportions, a pilot project coordinated by the University of Palermo tested the use of Pleurotus ostreatus (the common oyster mushroom) for the degradation of plastics and other persistent organic waste. The results demonstrated that this fungus is capable of degrading polyethylene (the most common plastic material) in significantly shorter times compared to natural processes. Furthermore, the mycelium showed the ability to accumulate heavy metals present as additives in plastics, helping to decontaminate the area. After 12 months of treatment, the produced fungal biomass was appropriately treated and disposed of as special waste, completing the remediation process.

Remediation of agricultural sites in Lombardy with mycorrhizal fungi

In Lombardy, the region with the highest concentration of intensive livestock farming and agricultural activities, soils often show high levels of nitrates, phosphates, and antibiotic residues. A project coordinated by the Parco Tecnologico Padano tested the use of mycorrhizal fungi to improve the quality of agricultural soils and reduce the pollutant load. Mycorrhizae, symbioses between fungi and plant roots, not only improve nutrient uptake by crops but also accelerate the degradation of xenobiotic organic compounds. The results showed a 40% reduction in nitrate leaching into groundwater and a significant decrease in the persistence of antibiotics in the soil.

For those wishing to learn more about mycorrhizal symbioses and their applications, the website of the Italian Botanical Society offers valuable resources and updates on research in this field.

Fungal species most used in regeneration projects

Not all fungi possess the same bioremediation capabilities. Research has identified species particularly effective for specific types of contamination:

Advantages and limitations of soil regeneration with fungi

The mycological approach to soil remediation offers numerous advantages compared to conventional technologies, but it also presents some limitations that are important to consider.

Advantages of bioremediation with fungi

The main advantages of using fungi in soil regeneration include:

Environmental Sustainability: unlike chemical or physical remediation techniques, bioremediation with fungi does not introduce additional chemicals into the environment and does not produce hazardous waste.

Contained Costs: bioremediation techniques have significantly lower costs compared to conventional technologies such as incineration or soil washing. Savings of 40-70% on remediation costs are estimated.

Preservation of Soil Structure: unlike excavation and landfill disposal, in situ bioremediation preserves the structure and fertility of the soil, keeping the soil ecosystem intact.

Versatility: fungi can be used to treat a wide range of contaminants, often in mixed contamination conditions where other technologies would be ineffective.

Limitations and challenges

Despite the many advantages, the use of fungi in remediation presents some limitations:

Long Timeframes: bioremediation processes generally require longer times compared to conventional technologies, which can be a limitation in emergency situations.

Optimal Environmental Conditions: the effectiveness of fungi depends on environmental factors such as temperature, humidity, pH, and nutrient presence, which must be maintained within optimal ranges.

Management of Contaminated Biomass: fungi that accumulate contaminants, especially heavy metals, must be properly collected and disposed of as hazardous waste.

Public Acceptance: the use of fungi, especially if genetically modified, may encounter cultural resistance and negative perceptions from the public.

Future perspectives and research in Italy

Research on bioremediation with fungi in Italy is rapidly evolving, with new frontiers opening thanks to advances in genomics and synthetic biology. Future perspectives include the development of genetically modified fungal strains with enhanced degradative capabilities, the integration of mycological techniques with other remediation technologies, and large-scale application in complex industrial contexts.

In particular, the synergy between fungi and hyperaccumulator plants (mycorrhiza-assisted phytoremediation) represents one of the most promising directions for the treatment of soils contaminated with heavy metals.

Degraded soils and decontamination: Italy as a pioneer.

The regeneration of degraded soils through the use of fungi represents an extraordinary example of how nature can provide effective and sustainable solutions to problems created by humans.

The pilot projects launched in Italy are demonstrating that this technology is not only technically feasible and economically advantageous but can also open new opportunities for economic development in sectors such as the green economy and environmental biotechnology. With the right research support and a favorable regulatory framework, Italy could position itself as a European and world leader in this innovative sector, simultaneously contributing to the reclamation of its territory and the creation of knowledge and skilled employment.

For more information on biological remediation techniques and Italian regulations, you can visit the website of the Ministry of the Environment and Energy Security.