1. As food: Mushrooms containing protein and vitamins are used as human food. There are about 200 species of fungi that are edible to humans. Mushroom (Agaricus, Volvariella), truffle, morel (Morchella) etc. fungi are used as food in different countries of the world including Bangladesh. Edible mushrooms for humans are Agaricus bisporus and Agaricus campestris. Their nutritional quality is good.
2. Decomposer: Fungi act as decomposers in ecosystems. They rapidly decompose the dead bodies of plants and animals into organic matter. So they are called transformative. They grow on dead bodies and feed on them. So they are called Saprophage.
3. Medicine
(i) Penicillium and streptomycin (antibiotics) are prepared from Penicillium notatum and Penicillium chrysogenum. Griseofulvin is produced from Penicillium griseofulvum and actinomycetes from Streptomyces griseus. Besides, antibiotics like chloromycin, neomycin, aureomycin etc. are made from fungi.
(ii) Ergot is prepared from Claviceps purpurea. It is used to hasten abortion and stop bleeding after childbirth.
(iii) Steroid drugs are prepared from Aspergillus fungi. It is used to treat arthritis.

(iv) Cyclosporine drug is prepared from Tolypocladium inflatum. Its trade name is Neoral. It is used to transplant human organs.
(v) Mushrooms have the ability to reduce diabetes. Magic mushrooms contain psilocin and psilocybin. Psilocin and psilocybin are the main components of hallucinogens. Hallucinogens relieve the body of depression.
4. Pesticides: Different types of pesticides are made from fungi. It is used for pest control. Such as Empusa sepulchralis, Isaria ferinosa, Ascherromyces deyroides.
5. Organic acid: Citric acid, malic acid, fumaric acid, oxalic acid, gluconic acid etc. are produced from different species of Penicillium. Diastase and oxalic acid from Aspergillus niger, gibberellic acid from Gibberella fujikuroi and invertase enzyme from Saccharomyces are available.
6. Hormone: Gibberellin hormone is obtained from the fungus Gibberella fujikuroi. It promotes plant growth.
7. Enzyme production: Aspergillus flavus and Aspergillus oryzae fungi produce digetin, polyzyme and diastase enzymes.
8. Protein production: Yeast cake is made by cultivating Saccharomyces cerevisiae and Candida urtilis fungi through molasses and ammonia mixed culture. Yeast cake is rich in protein. It contains 15% meat.
9. Vitamine production: Vitamin-B is produced from Ashbya gossypii fungus, Vitamin-C from Aspergillus niger and Vitamin-D from yeast.
10. Soil fertility: Fungi feed on dead plant and animal remains and decaying organic matter. These fungi break down complex organic compounds into simple inorganic substances. As a result, soil fertility increases. 8 inches of fertile soil can contain a ton of fungi and bacteria.
11. Industrial role
The role of fungi in industry is-
(i) Various species of Saccharomyces are used in making vitamin B and C in bread, cake, gheeserin etc. It is used to flavor chocolate made from cocoa beans.
(ii) Saccharomyces cerevisiae and Aspergillus oryzae fungi are widely used in alcohol production.
(iii) Saccharomyces are used to produce alcohol from sugarcane, dates, palm and grapes in the fermentation process.
(iv) Penicillium camemberti and Penicillium rosqueferti are used to make sourdough cheese.
(v) Mucor rouxii is used to break down sugar to produce sugar.
(vi) Odium lactis species of fungus is used to make plastics.
(vii) Organic acids, vitamins and enzymes are produced from Aspergillus and Penicillium fungi.
(viii) Saccharomyces are widely used in bakery to make bread and cakes. That is why it is called Brewer’s yeast.
12. Rock pulverized : Fungi live as cohabitants in lichens. Lichens play an important role in weathering rocks. Crushed rock contributes to soil formation.
13. Conservation of environment: Fungi detoxify the environment by breaking down the pollutants in the environment. This process is called Bioremediation. Fungi break down waste materials and return carbon and other elements to the environment which are then used by green plants. As a result, the environment remains clean and safe for living organisms.
14. Basic research: Saccharomyces cerevisiae strains AH-109, PJ69-4 alpha, Y187 etc. are used in advanced research in molecular biology. Besides, Saccharomyces, Ascobolus, Neurospora etc. are used in genetic research.

Plasmogamy results in the cell having two haploid nuclei. This condition is called dikaryon. The nucleus is two heterokaryons (+, -) in nature. The two nuclei move closer together and fuse. The union of nuclei is called karyogamy. Karyogamy results in the formation of a diploid nucleus.

The union of protoplasm of two cells or gametes is called plasmogamy. The two gametes approach each other and their protoplasm fuses.

1. Plasmogamy : The union of protoplasm of two cells or gametes is called plasmogamy. The two gametes approach each other and their protoplasm fuses.
2. Karyogamy: Plasmogamy results in the cell having two haploid nuclei. This condition is called dikaryon. The nucleus is two heterokaryons (+, -) in nature. The two nuclei move closer together and fuse. The union of nuclei is called karyogamy. Karyogamy results in the formation of a diploid nucleus.
3. Meiosis: The diploid zygote divides by the process of meiosis to form a new zygote.

If plasmogamy, karyogamy and meiosis do not occur sequentially in the sexual reproduction of fungi, it is called parasexuality or pseudosexuality. Such intercourse is called a parasexual cycle.

Somatogamy in advanced fungi behaves like genitalia and their protoplasts fuse. This is called somatogamy. Somatogamy results in a dikaryotic condition. For example, Aspergillus

Fertilization unit called spermatium is formed in some fungi. They are small, unicellular and have one nucleus. The spermatozoa come into contact with the female genitalia through water, air or insects and the wall of the contact site dissolves to form a pore. Through this pore the protoplast of the spermatium unites with the protoplast of the female genitalia. eg Puccinia.

Two gametangia of the opposite sex of the fungus touch each other and the wall of the contact area dissolves to form a duct. Through this duct the male gamete joins the female gamete. In this case, the genitals do not lose their respective properties. Such as Saprolegnia, Pythium, Phytophthora etc.

Two gametangia of fungi of opposite sex come close to each other and complete sexual reproduction by joining. In this case, the genitals lose their respective properties. Such as Mucor, Rhizopus, Yeast etc.

The process of sexual reproduction in which a small and motile pongygamete unites with another large and immobile female gamete is called oogamy.