11th Class Biology Biological Classification And System Of Classification / जैविक वर्गीकरण और वर्गीकरण की प्रणाली Economic Importance

(1) Harmful aspects

Crop diseases : Several important crop plants are destroyed by fungal diseases. Some important ones are listed here under :

Fungal disease in plants

Diseases in human beings : Several diseases in human beings are found to be caused by fungi, infecting different parts of the body. Some of them are given here under as :

Fungal disease in human

Spoilage of food : Some forms like Rhizopus, Mucor, Aspergillus, Cladosporium grow on food articles and spoil them. Cladosporium grows even at a temperature of – 6°C.

Aflatoxins : They are produced mainly by Aspergillus flavus and A. parasiticus. They are well know for their carcinogenic effect. e.g., Aflatoxin B₁, B₂, M₁, M₂, G₁, G₂.

Poisonous fungi : Some fungi are extremely poisonous e.g., Amanita phalloides ('death cup'), A. verna and Boletus satanus. Forms like Coprinus, Psilocybe are less poisonous. The fungus Amanita phalloides produces toxins like a-amanitin, phalloidin etc. which are very poisonous.

Ergotism : The fungus causing 'ergot' disease of rye (Secale) is Cleviceps purpurea. It contains many poisonous alkaloids in their sclerotia. It causes poisoning in human beings. It's acute condition is called as 'St. Anthony's fire'.

Hallucinogenic drugs : The hallucinogenic drug LSD (Lysergic acid diethylamide) is extracted from Cleviceps purpurea as also from Inocybe. Besides, the mushroom Amanita muscaria is also hallucinogenic.

Rotting of wood : Rotting of wood is caused due to degradation of lignin and cellulose. It is brought about fungi like Polyporus sp., Fomes sp. and Ganoderma sp., Forms like Fusarium, Penicillium leave stains on the wood.

Allergies : Spores of Mucor, Aspergillus, Penicillium, Puccinia etc., present in the atmosphere cause allergies.

Deterioration of articles : Forms like Aspergillus, Cladosporium, Rhizopus, Chaetomium, Alternaria deteriorate cork, rubber, leather, textile and even plastics.

(2) Useful aspects

Food : Forms like Agaricus bisporus, Morchella esculenta, Lentinus edodes, Clavatia gigantia, Volvariella volvacea are edible. The yeast Saccharomyces cerevisiae is used for making 'yeast cake'. When mixed with cereal flour, the yeasts produce a preparation called incaparina. The Single Cell Protein (SCP) obtained from yeasts, Penicillium, Fusarium etc. are used as substitute of protein food. Rhizopus oligosporus when processed with soyabeans yield a food preparation called 'tempeh'. It has high protein contents.

Flavoring of food : Penicillium roquefortii and P. camemberti are employed for flavouring cheese.

Brewing and baking : Yeasts are generally used in bakeries and breweries. e.g., Saccharomyces cerevisiae.

Organic acids : Several organic acids are commercially produced by fungi, some of which are given hereunder :

Fungi as a source of organic acids

Antibiotics : The antibiotics are chemicals produced by living organisms that kill other living organisms. The first known antibiotic is penicillin that was extracted from Penicillium notatum by A. Flemming, (1944). Raper (1952) also extracted the same antibiotic from P. chrysogenum. Besides, several other antibiotics have been extracted since then.

Fungi as a source of antibiotics

Other chemicals : Various chemicals have been obtained from different kinds of fungi. Yeast are good source of glycerol and enzymes like zymase, invertase and lipase. Cellulases are obtained from Aspergillus. Some alkaloids are also obtained from fungi e.g., Ergotinine, Ergotetrine and Ergobasine from Cleviceps purpurea. Gibberellins (plant hormones) are obtained from Gibberella fujikuroi. Another hormone, trisporic acid is obtained from Mucor mucedo.

Biological assays : The fungi can detect the presence of certain chemicals present in the medium even in traces e.g., Aspergillus niger for Mn, Pb, Zn, Cu, Mo etc.

Vitamins : Various vitamins have been obtained from different kind of fungi.

Fungi as source of vitamins