Fungi (Singular: Fungus) Are a Major Group

Fungi (singular: fungus) are a major group of living organisms that were previously considered to be plants by biologists but are now classified in a separate category of 'Fungi Kingdom.' Fossil discoveries suggest that they were present on Earth at least 550 million years ago and may even have evolved earlier. They occur in all kinds of environments around the world and according to an estimate as many as 1.5 million species of fungi may exist on the Earth. (Hawksworth, quoted by Blackwell et al.) Some of the better known types of fungi include mushrooms, rusts, smuts, puffballs, truffles, morels, molds, and yeasts. They perform both useful as well as harmful functions. For example, by breaking down dead organic material, they are an important part of the carbon cycle in nature. On the other hand, they cause a number of animal and plant diseases that are notoriously difficult to treat. This paper is a brief discussion of fungi, how they are different from plants and animals, their classification, their benefits, and harmful effects.

How Fungi are Different from Plants and Animals

Unlike plants and animals, fungi obtain food by absorbing nutrients from an external source and are placed in a separate category of organisms mainly due to this characteristic. Fungi lack chlorophyll (the green pigment that enables plants to make their own food) and cannot synthesize their own food in the way that plants do. They differ from animals because fungi cannot ingest their food and have to break down their food outside their bodies by releasing digestive enzymes and then absorbing the dissolved food through their cell walls. (Blackwell et al.)

Classification

Fungi are usually classified according to the way in which they reproduce. The four main divisions being: the Chytridiomycota (chytrids), Zygomycota (bread molds), Ascomycota (yeasts and sac fungi), and the Basidiomycota (club fungi) with Ascomycota being the largest group of fungi having around 50,000 known species. ("Fungi: Life History and Ecology")

Another way in which they can be classified is the method of feeding adopted by them. For example some fungi live as "parasites" by feeding on living plants, animals, or other fungi, while others feed on dead organisms or substances containing organic compounds, such as starch and cellulose. Such fungi are called saprobes or "saprophytes." A third category of fungi form specialized relationship with other plants or animals to obtain their food. Such fungi together with the roots of the plants they inhabit are known as "mycorrhizae" or "fungal roots." In this mutually beneficial relationship, the fungi soak up water and essential minerals for the plants, and in return, the plants provide energy-rich sugars manufactured through photosynthesis to the fungi. (Ibid.)

Usefulness

1. Recycling:

As mentioned earlier fungi play an important role in the completion of the carbon cycle and in maintaining the natural ecosystems. They do so by decomposing organic matter, breaking down plant and animal remains and wastes into their chemical components and thus play a critical role in the recycling of minerals and carbon.

2. Antibiotics, Fermenting Agent & Food Source:

Fungi are used for producing of antibiotics. In fact, the first ever antibiotic, the penicillin, was derived from a fungal mold and was initially effective against a wide range of disease-causing bacteria.

Other fungi are extensively used in the manufacture of foods. Yeast, for example, is used to ferment fruit juice and produce wine. It is also used for manufacturing beer, and bread and certain types of fungal molds are used to ripen some types of cheese. In addition, fungi are also an important food source with some mushrooms and truffles being highly prized delicacies.

3. Cleaning Agent:

In recent times, the role of fungi as an important tool in cleaning the environment has been realized. It has been successfully used for controlling insects, and other organisms that cause damage and disease to agricultural crops. They are also used to decompose the organic material in pollutants and thus detoxify them. (Ammirati and Seidi, para on "Uses of Fungi")

Harmful Effects

Fungi cause a number of plant and animal diseases. It is estimated than more than half of major crop diseases are caused by fungal growths and cause billions of dollars of economic loss every year. Such diseases attack seeds, crops, young as well as mature plants including forest trees and even wood structures. Fungal diseases of plants include rusts, smuts, and leaf, root, and stem rots.