Fungi: Definition: Types of Fungi & Their Importance

Fungi: During rainy seasons, you’ve probably noticed some sort of umbrella-like structure growing on dead woods, grassland, etc. They are called fungus (pl. Fungi). Fungi are a distinct kingdom of eukaryotic or prokaryotic, mostly multicellular organisms that lack chlorophyll. There are many thousands of types of fungi that share our environment, and we are constantly being exposed to fungi in the air we breathe, the food we eat, and the water we drink. which includes the yeasts, rusts, smuts, mildews, molds, and mushrooms.

After the evolution of Monerans and Protists, it was assumed that Fungi were the first to evolve from Protists. There are about 100000 species in the Kingdom Fungi. In this article, we have covered the definition, characteristics, importance and types of Fungi in detail.

Solve & Practice Questions on The Kingdom Fungi Concept

What are Fungi?

Fungi are a group of spore-producing organisms feeding on organic matter, including moulds, yeasts, mushrooms, and toadstools. The Kingdom Fungi (or Mycota) is a group of living organisms that are multicellular, eukaryotic, and heterotrophic in nutrition. Fungi live mostly as saprobiotic or often parasites. Fungi show great diversity in morphology and habitat. Fungi are among the most widely distributed organisms on Earth and are of great environmental and medical importance.

Study of Fungi

The branch of biology which studies the various groups of fungi is known as Mycology.  It involves the study of genetic and biochemical properties, taxonomy, and the use of fungi as the source of medicines, food, etc. as well as their harmful effects like toxicity and infection.

A scientist who studies fungi is called Mycologist. Pier Antonio Micheli is known as the Father of Mycology. Prof. C. V. Subramanian is one of the well-known Indian Mycologists.

Characteristics of Fungi

The characteristics of fungi are as follows:

1. Fungi can be found everywhere, i.e., they are cosmopolitan.
2. Fungi are mostly terrestrial, but few are aquatic also.
3. Fungi mostly grow in warm and humid places like wood, the bark of trees, dung, etc.
4. Depending on the mode of nutrition, fungi can be saprophytic or parasitic.
   a. Saprophytic fungi grow on dead and decaying organic matter (plants and animals). Ganoderma, Polyporus are wood-rotting fungi.
   b. Parasitic fungi live inside or on the body of the host organism (plant or animal). Albugo, Phytophthora are parasitic fungi.
   c. Coprophagous fungi feed on animal excreta. Peziza is an example of a coprophagous fungus.
5. The vegetative phase of a fungus is called thallus, which is not differentiated into distinct roots, stems, and leaves.
6. The thallus may be unicellular, like in Saccharomyces cerevisiae or Yeast or filamentous as in most fungi.
7. The thallus is formed of a large number of fine, tubular, thread-like filaments called hyphae (sin. hypha).
8. The hyphae may be aseptate (without walls) or septate (with walls). Aseptate hyphae are multinucleated (coenocytic).

1. The hyphae are interwoven loosely to form mycelium (Pl. mycelia).
2. The cell wall of fungi is made up of chitin. 
3. The reserve food material in fungi is glycogen.

Reproduction in Fungi

Reproduction in fungi may take place by vegetative, asexual, or sexual means.

1. Vegetative Reproduction in fungi may occur by the following methods:

2. Asexual Reproduction in fungi takes place by the formation of the following asexual spores:

3. Sexual Reproduction takes place in almost all types of fungi except Deuteromycetes (also called Fungi imperfecti). The sex organs that produce gametes are called gametangia (e.g., gametangium). For e.g., Rhizopus, Synchytrium, Neurospora, etc. The sexual cycle involves the following three stages:

1. Plasmogamy or the fusion of protoplasms.
2. Karyogamy or the fusion of nuclei.
3. Meiosis or the reduction division. Sexual reproduction results in the formation of the following haploid spores, which are produced in distinct structures called fruiting bodies:
   a. Ascospores
   b. Basidiospores
   c. Oospores

Classification of Fungi

Kingdom Fungi can be divided into various classes on the basis of the morphology of mycelium, mode of spore formation, and fruiting bodies. There are four different groups of fungi which are as follows:

Class	Description and Example	Example
Myxomycetes	Called Slime moulds. Body unicellular. Physarum.
Phycomycetes	Called algal-fungi. Albugo, Rhizopus, Mucor.
Ascomycetes	Called sac-fungi. Neurospora, Aspergillus, Claviceps.
Basidiomycetes	Called club-fungi. Puccinia, Agaricus, Ustilago.
Deuteromycetes	Called Fungi Imperfecti. Colletotrichum, Trichoderma, Alternaria.

Important Fact!

1. Mushrooms are found in moist humus-rich soil, open fields and grasslands. They develop in rings called fairy rings.
2. Myxomycetes are protistan fungi. They are essentially unicellular. They are commonly called Fungus-like Protists.

Myths about Fungi

1. It is important to learn that Phycomycetes and Zygomycetes are not identical.
2. The class Phycomycetes has become obsolete nowadays. 
   a. There exists Zygomycetes, Chytridiomycetes, Plasmodiophoromycetes, Hyphochytridiomycetes, Trichomycetes and Oomycetes.

Economic Importance of Fungi

Some fungi are extremely beneficial to humans, while others are extremely harmful.

Useful Activities of Fungi

1. Some fungi, such as Agaricus campestris (edible mushroom), Agaricus bisporus (white button mushroom), and others, are used as food since they are high in protein, vitamins, and minerals.
2. Some fungi are used for the production of useful products in industries like Saccharomyces (Baker’s Yeast), Aspergillus niger (production of citric acid), Penicillium camemberti (for flavouring cheese), etc.
3. Some fungi are also used in agriculture like Trichoderma (to increase soil fertility), Dactylella (good biological control agent).
4. Several fungi are used in the production of medicines, as shown in the table below: 

1. Fungi play a very important role as decomposers in the detritus food chain without which the Earth would have been full of dead bodies.
2. Fungi also help in recycling nutrients like carbon, nitrogen, etc. in the ecosystem.

Harmful Activities of Fungi

Fungi are the causal organisms of many diseases in living beings (i.e., both plants and animals).

Association of Fungi with Other Organisms

Fungi are often associated with other organisms in a positive, beneficial manner. Lichens are a symbiotic association of algae and fungi and play an important role in ecosystem development. Mycorrhizae are fungal associations with roots of higher plants. These fungi help in the absorption of nutrients from the soil.

Summary

From this article, we found that Fungi are one of the most diverse and omnipresent living organisms. They are achlorophyllous and show absorptive and heterotrophic nutrition. They are most harmful to both plants and animals. Some are economically important and are even consumed. Some forms show a positive association with other living organisms and benefit mutually. 

Frequently Asked Questions (FAQs) On Fungi

Q.1. Write 2 fungi examples with scientific names.
Ans: Two examples of fungi along with the scientific names are: Yeast- Saccharomyces cerevisiae and White button mushroom- Agaricus bisporus.

Q.2. What is the simple definition of Fungi?
Ans: Fungi are defined as a group of unique living organisms which are mostly multicellular, eukaryotic, and heterotrophic organisms. They are neither plants nor animals. They do not have chlorophyll of their own.

Q.3. What are the 4 types of fungi?
Ans: The four types of fungi are: i) Phycomycetes, ii) Ascomycetes, iii) Basidiomycetes, and iv) Deuteromycetes.

Q.4. What are the 5 characteristics of fungi?
Ans: i) They are multicellular and eukaryotic organisms, ii) They do not have chlorophyll of their own, iii) Cell wall is made up of chitin, iv) Their body is formed of thread-like filamentous structures called hyphae, and v) Their mode of nutrition is saprophytic or parasitic.

Q.5. Do fungi die?
Ans: Yes, fungi die when they complete the process of forming spores by the meiosis process. After the spores get spread, the remaining parts of the fungi then decompose in the soil.

Q.6. How do fungi obtain their nutrition?
Ans: Fungi obtain their nutrition from the dead and decaying organic matter (plants and animals). They secrete enzymes that decompose the complex organic matter into simple absorbable inorganic components.

Q.7. State any two diseases caused by fungi.
Ans: Candidiasis and Aspergillosis are two examples of fungal diseases.

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