7.5.4 Ecological Impacts of Fungi
Decomposition and recycling of materials Fungi and bacteria are biosphere decomposers. Both make significant contributions to the ecological balance of our world. They decompose organic matter and release the substances locked in the dead bodies of animals and plants for circulation in the ecosystem.
Fungi possess a potent enzyme system that helps in splitting tough organic compounds that can not be digested by most other living things, e.g., lignin (in wood). The released substances become available to the next generation of organisms. They also release large amounts of CO, in the air by decomposition, which is used for the synthesis of organic food by green living things (plants, algae, and cyanobacteria).
Thus fungi recycle nutrients in nature and are called recyclers. The fungi clean the earth by removing the organic matter and because of this characteristic they have earned the name "scavengers".
7.5.5 Pathogenic Role of Fungi
The pathogens are disease-causing organisms. Many fungi are also pathogenic and cause diseases in plants, animals, and human beings.
Plant diseases:
Fungi cause many plant diseases, some of which are very important. All plants are susceptible to many fungal infections. The most common fungal diseases of cereals are rusts and smuts caused by Puccinia and Ustilago respectively which belong to the group Basidiomycota. Sac fungi cause diseases like powdery mildew, apple scabs, chestnut blight, Dutch elm disease, red rot of sugar cane, and brown rot which attack plums, peaches, apricots, and cherries.
Fungal diseases of animals:
Fungi cause many diseases in animals, some of which are: Ringworms in dogs and horses are caused by the species of Trichophyton rubrum and Microsporum audouinii. Aspergillus sp. causes abortion in many animals. Saprolegnia parasitica is a parasite of carp and salmon fish.
Fungal diseases of humans:
Fungi infect all parts of the human body, especially the skin. Rhizopus and Mucor species cause the infection of the lungs (Histoplasmosis), brain, and digestive tract. The cause of dandruff is Microsporum furfur. Candida species causes candidiasis (causes infection in the mucus membrane of the throat, mouth, vagina, etc.). Neurospora and Fusarium cause infection of the corneal tissues of the eyes. Aspergillus fumigatus causes aspergillosis which like AIDS destroys the immune system. Aspergillus flavus produces aflatoxin, a cancer-causing mycotoxin in improperly stored grains of peanut, corn, etc. Purple ergot rye causes ergotism, which causes nervous spasms, convulsions, psychotic delusion, and even gangrene. The athlete's foot is caused by Tinea pedis.
SUMMARY
A kingdom Protista is a polyphyletic group of organs with common ancestors that do not share a single.
⚫ Kingdom Protista includes organisms that are animal-like, plant-like, and fungus-like.
⚫ Protists may be unicellular or multicellular and may be microscopic or very large. • Most plantlike protists can make their own food through photosynthesis.
⚫ Protozoa, animal-like protists have various structures that help them to move, such as flagella, pseudopodia, or cilia. Some animal-like protists can cause diseases such as malaria.
⚫ Fungus-like protists decompose organic matter. These protists have an important role in recycling nutrients through ecosystems. Unlike fungi, fungus-like protists can move during part of their life cycle. Fungus-like protists include slime molds and water molds.
⚫ Fungi are eukaryotic organisms that appeared on land over 450 million years ago. They are heterotrophs and contain neither photosynthetic pigments such as chlorophylls nor organelles such as chloroplasts. Since they feed on decaying and dead matter, they are saprobes.
⚫ Fungi are important decomposers and release essential elements into the environment. External enzymes digest nutrients that are absorbed by the body of the fungus called thallus.
⚫ A thick cell wall made of chitin surrounds the fungal cell.
⚫ Fungi can be unicellular as yeasts or develop a network of filaments called mycelium, often described as mold.
⚫ Most species of fungi multiply by asexual and sexual reproductive cycles and display an alternation of generations.
⚫ The divisions of fungi are the Zygomycota, Ascomycota, and Basidiomycota.
⚫ Fungi establish parasitic relationships with plants and animals. Fungal diseases can decimate crops and spoil food during storage.
⚫ Fungi have colonized all environments on Earth but are most often found in cool, dark, moist places with a supply of decaying material.
⚫ Many successful mutualistic relationships involve a fungus and another organism. They establish complex mycorrhizal associations with the roots of plants. Lichens are a symbiotic relationship between a fungus and a photosynthetic organism, usually an alga or cyanobacterium.
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