Detrimental effects of Fungi

▶Biodeterioration

The same extracellular enzymes that are important in the degradation of leaf litter and the recycling of nutrients in the biosphere can cause massive economic losses when they occur in circumstances where they are not wanted. Fungi can attack and utilize as substrates paper, cloth, leather, and hydrocarbons, but also can cause degradative change in other materials, for instance, glass and metal, because of their ability to produce acid as they grow. The supply of water is a key control point in these processes, and keeping substrates dry is an effective way of avoiding these changes.

▶Plant disease

Fungi are capable of attacking all plant species, causing serious damage and in some circumstances even death. In crop production over half of potential crop yield is lost to plant pathogens, most of it to fungal disease. In storage, up to one-third of the harvested product can be lost to post-harvest disease, again mostly as a result of the activities of fungi. Use of fungicides can reduce both pre- and post-harvest disease, and plant breeding programs can introduce disease-resistant strains of crop plants. Post-harvest losses can be reduced by storage of products at low temperatures and low moisture levels.

▶Animal and human disease

Human and animal epidermis can be attacked by fungi, causing superficial damage and discomfort like ringworm infections, athlete’s foot, and thrush. Other deeper, systemic fungal infections of the lung and central nervous and lymphatic systems cause much more serious diseases, for example, aspergillosis, coccidiomycosis, blastomycosis, histoplasmosis, and pneumocystis pneumonia are all caused by fungi. Although most humans experience superficial fungal infections and survive, these deeper diseases are especially dangerous for the immunocompromised patient after transplantation, and the HIV-positive population.

▶Fungal toxicosis

Accidental or deliberate consumption of wild fungi or fungally contaminated food can lead to poisoning or toxicosis of the consumer because some fungi naturally contain toxic metabolites called mycotoxins. Deliberate toxicosis can arise from consumption of mushrooms and toadstools that are known to contain naturally hallucinatory drugs like psilocybins, which lead to euphoric states followed by extreme gastrointestinal distress. Accidental consumption of mis-identified fungal fruit bodies can lead to fatal mushroom poisoning from fungal toxins, causing total liver failure between 8 and 10 hours later. Consumption of food accidentally contaminated by fungal metabolites also leads to human and animal death. For instance, rye flour contaminated by the ergots of the fungus Claviceps purpurea leads to the symptoms of St Anthony’s fire, where peripheral nerve damage is caused by the presence of ergometrine in the fungal tissue. This can be followed by gangrene of the limbs and death. Detection of fungal mycotoxins such as ochratoxin in apple juice and aflatoxin in peanuts has also caused problems for food producers and consumers and has forced improvements in product processing.