Fungi – Structure, Classification and Uses
What are Fungi?
Microorganisms such as yeasts, molds, and mushrooms are fungi, which are eukaryotic organisms. These organisms belong to the kingdom Fungi. The organisms found in the Kingdom Fungi have a cell wall and are ubiquitous and among living organisms, they are classified as heterotrophs. To name a few, fungi cause the appearance of black spots on bread that has been left outside for a few days, mushrooms, and yeast cells, which are commonly used in the production of beer and bread. They are also found in the majority of skin infections and fungal diseases. If we look closely, we can see that all of the examples we cited involve moist conditions. As a result, we can conclude that fungi typically grow in moist, warm environments. Let us now take a closer look at the structure of fungi, classification of fungi and their characteristics
Structure of Fungi
1. Fungi structure can be explained in the following ways:
2. Except for yeast cells, almost all fungi have a filamentous structure.
3. They can be either single-celled or multicellular organisms.
4. Fungi are made up of long thread-like structures called hyphae. Mycelium is a mesh-like structure formed by these hyphae.
5. Fungi have a cell wall composed of chitin and polysaccharides.
6. The cell wall is made up of a protoplast that differentiates into other cell components such as the cell membrane, cytoplasm, cell organelles, and nuclei.
7. The nucleus is dense and clear, with chromatin threads running through it. A nuclear membrane surrounds the nucleus.
13 Characteristics of Fungi
1. Fungi have the following important characteristics:
2. Fungi are eukaryotic organisms that are non-vascular, non-motile, and heterotrophic
3. They can be unicellular or filamentous in nature
4. They reproduce through spores
5. Fungi exhibit the alternation of generation phenomenon.
6. Fungi lack chlorophyll and thus cannot photosynthesis.
7. Fungi use starch to store their food.
8. Chitin biosynthesis occurs in fungi.
9. Fungi nuclei are extremely small.
10. The fungi do not have an embryonic stage. They grow from the spores.
11. Sexual or asexual reproduction is used.
12. Some fungi are parasitic, thereby infecting the host.
13. Fungi produce a chemical called pheromone, which promotes sexual reproduction.
14. Mushrooms, molds, and yeast are some examples of fungi.
Classification of Fungi
The classification of fungi based on their mode of nutrition is very common among biologists. In this post, we shall classify fungi according to their modes of nutrition and spore formation.
Mode of Nutrition
Depending on the mode of nutrition, fungi can be divided into three groups based on nutrition.
Saprophytic Fungi
Saprophytic fungi get their nutrition by feeding on dead organic matter. Rhizopus, Penicillium, and Aspergillus are a few examples of saprophytic fungi.
Parasitic Fungi
Fungi that are parasitic feed on other living organisms (plants or animals) and absorb nutrients from their host. Taphrina and Puccinia are two examples of parasitic fungi.
Symbiotic Fungi
Symbiotic fungi live in an interdependent relationship with other species that benefits both parties. Lichens and mycorrhizae are two examples of symbiotic fungi.
Lichens are a symbiotic relationship between algae and fungi. In this case, algae and fungi benefit from each other because fungi provide shelter for algae and algae provide carbohydrates for fungi.
Mycorrhiza is a symbiotic relationship that exists between fungi and plants. Fungi improve plant nutrient uptake, whereas plants provide organic molecules such as sugar to the fungus.
Formation of Spores
The classification of fungi can also be based on their formation of spores. Fungi can be classified as follows:
Zygomycetes
Zygomycetes are formed by the fusion of two different types of cells. The sexual spores are called zygospores, and the asexual spores are called sporangiospores. The septa of zygomycetes are missing from the hyphae. Mucor is an example of a zygomycete.
Ascomycetes
Ascomycetes are also known as sac fungi. Coprophiles, decomposers, parasites, and saprophytes are all possible types of ascomycetes. Ascospores are the sexual spores. Conidiospores are responsible for asexual reproduction. Saccharomyces is an example of ascomycetes.
Basidiomycetes
Mushrooms are the most common basidiomycetes, and they mostly live as parasites. Basidiospores are responsible for sexual reproduction. Conidia, budding, and fragmentation are all methods of asexual reproduction. Agaricus is an example of basidiomycetes.
Deuteromycetes
Deuteromycetes are also known as imperfect fungi because they do not reproduce in the same way as other fungi. They are not sexually reproducing. Conidia are used for asexual reproduction. Trichoderma is an example of deuteromycetes.
Reproduction in Fungi
Fungi reproduce in both sexual and asexual ways. The sexual mode of reproduction is known as teleomorph, while the asexual mode of reproduction is known as anamorph.
Fungi reproduce vegetatively through budding, fission, and fragmentation.
Asexual reproduction occurs through the use of spores known as conidia, zoospores, or sporangiospores.
Sexual reproduction is accomplished through the use of ascospores, basidiospores, and oospores.
In the kingdom, the traditional mode of sexual reproduction is not always observed. The fusion of two haploid hyphae does not result in the formation of a diploid cell in some fungi. In such cases, an intermediate stage known as the dikaryophase appears.
Uses of Fungi
Fungi are one of the most important groups of organisms on the planet because they play an important role in the biosphere and have significant economic value due to both their beneficial and harmful effects.
The following are some of the most important applications for fungi:
Recycling
They play a significant role in the recycling of dead and decayed matter.
Food
The mushroom species that have been cultured are edible and are consumed by humans.
Medicines
Many fungi are used to make antibiotics and to treat diseases in humans and animals. The antibiotic penicillin is derived from the fungus Penicillium.
Biocontrol Agents
Fungi are biocontrol agents that exploit insects and other small worms and aid in pest control. Fungi spores are used as a crop spray.
Food Spoilage
Fungi play an important role in organic material recycling and are also responsible for significant spoilage and economic losses in stored food.
Types Of Fungi
The following are some common fungi:
- Yeasts
- Mushrooms
- Moulds
