- The term “mycology” is derived from the Greek word “mykes” meaning mushroom. Therefore mycology is the study of fungi.
- Mycology is the branch of biology that specifically focuses on the study of fungi. It encompasses the scientific study of fungi, including their applications, interactions with other species, taxonomy, genetic and biochemical characteristics, and environmental importance. Mycologists study various aspects of fungi, including their structure, classification, identification, and their roles in disease, ecology, and industry.
- Fungi are a diverse group of organisms that include yeasts, moulds, mushrooms, and other fungal species. Mycology plays a crucial role in various fields such as medicine, agriculture, food production, environmental science, and industry. For example, mycologists study the beneficial aspects of fungi (such as their use in food production, fermentation, and medicine) as well as their detrimental impacts (such as crop diseases or infections in humans and animals).
Importance of Mycology
Identification of Fungal Infections:
- Mycology is essential for identifying and diagnosing fungal infections in humans, animals, and plants. Understanding the specific fungi responsible for infections is crucial for effective treatment and management.
Clinical Diagnosis and Treatment:
- In medical mycology, the study of fungi contributes to the diagnosis and treatment of fungal diseases in humans. This includes conditions such as fungal skin infections, respiratory infections, and systemic fungal infections, which may require antifungal medications.
Antifungal Drug Development:
- Understanding the biology and life cycles of fungi is crucial for the development of antifungal drugs. Mycologists contribute to the discovery and design of medications that target specific fungal pathogens while minimizing harm to the host.
Plant Pathology:
- Mycology is important in plant pathology, where it is used to study and manage fungal diseases affecting crops. Identification and control of plant pathogens are crucial for agricultural productivity and food security.
Biotechnological Applications:
- Mycology has biotechnological applications, including the production of enzymes, antibiotics, and other bioactive compounds. Fungi are used in various industrial processes, such as the production of citric acid, enzymes for food processing, and pharmaceuticals.
Food and Beverage Industry:
- Mycology is relevant to the food and beverage industry, where fungi can be used for fermentation processes. Yeasts, for example, are crucial in the production of bread, beer, and other fermented foods.
Beneficial Effects of Fungi
- Decomposition- nutrient and carbon recycling.
- Biosynthetic factories-The fermentation property is used for the industrial production of alcohols, fats, citric, oxalic and gluconic acids.
- Important sources of antibiotics, such as Penicillin.
- Some fungi are edible (mushrooms).
- Yeasts provide nutritional supplements such as vitamins and cofactors.
- Penicillium is used to flavour Roquefort and Camembert cheeses.
- Model organisms for biochemical and genetic studies. E.g., Neurospora crassa.
- Fungi (Leptolegnia caudate and Aphanomyces laevis) are used to trap mosquito larvae in paddy fields and thus help in malaria control.
- Saccharomyces cerevisiae is extensively used in recombinant DNA technology, which includes the Hepatitis B Vaccine.
Harmful Effects of Fungi
- Destruction of food, lumber, paper, and cloth.
- Animal and human diseases, including allergies.
- Plant diseases.
- Toxins produced by poisonous mushrooms and within food (Mycetism and Mycotoxicosis).
- Spoilage of agriculture produce such as vegetables and cereals in the godown.
- Damage the products such as magnetic tapes and disks, glass lenses, marble statues, bones and wax.
General properties of fungi
- They are eukaryotic, cells contain membrane-bound cell organelles including nuclei, mitochondria, Golgi apparatus, endoplasmic reticulum, lysosomes etc. They also exhibit mitosis.
- Have a rigid cell wall and are therefore non-motile, a feature that separates them from animals. All fungi possess cell walls made of chitin.
- Are chemoheterotrophs (require organic compounds for both carbon and energy sources) and fungi lack chlorophyll and are therefore not autotrophic.
- Fungi are osmiotrophic, they obtain their nutrients by absorption.
- They obtain nutrients as saprophytes (live off of decaying matter) or as parasites (live off of living matter).
- All fungi require water and oxygen and there are no obligate anaerobes.
- Typically reproduce asexually and/or sexually by producing spores.
- They grow either reproductively by budding or non-reproductively by hyphal tip elongation.
- Food storage is generally in the form of lipids and glycogen.
Classification of fungi
Kingdom Fungi are classified based on different modes. The different classification of fungi is as follows:
Based on mode of nutrition: Based on nutrition, kingdom fungi can be classified into 3 groups.
1. Saprophytic– The fungi obtain their nutrition by feeding on dead organic substances. Examples: Rhizopus, Penicillium and Aspergillus.
2. Parasitic– The fungi obtain their nutrition by living on other living organisms (plants or animals) and absorbing nutrients from their host. Examples: Taphrina and Puccinia.
3. Symbiotic– These fungi live by having an interdependent relationship with other species in which both are mutually benefited. Examples: Lichens and mycorrhiza. Lichens are the symbiotic association between algae and fungi. Here both algae and fungi mutually benefited as fungi provide shelter for algae and in reverse algae synthesise carbohydrates for fungi. Mycorrhiza is the symbiotic association present between fungi and plants. Fungi improve nutrient uptake by plants, whereas, plants provide organic molecules like sugar to the fungus.
Based on spore formation: Kingdom Fungi are classified into the following based on the formation of spores.
1. Zygomycetes– These are formed by the fusion of two different cells. The sexual spores are known as zygospores, while the asexual spores are known as sporangiospores. The hyphae are without the septa. Example – Mucor.
Medically important orders and genera include:
- Entomophthorales: Conidiobolus and Basidiobolus are involved in subcutaneous zygomycosis.
- Mucorales: Rhizopus, Mucor, Rhizomucor, Absidia and Cunninghamella are involved in subcutaneous and systemic zygomycosis (formerly called Mucormycosis).
2. Ascomycetes– They are also called sac fungi. They can be coprophilous, decomposers, parasitic or saprophytic. The sexual spores are called ascospores. Asexual reproduction occurs by conidiospores. Example – Saccharomyces.
Medically important genera include the:
- Teleomorphs of known pathogenic fungi e.g. Arthroderma (of Trichophyton and Microsporum), Ajellomyces dermatitidis (of Blastomyces dermatitidis), Pseudallescheria boydii (of Scedosporium apiospermum).
- Agents of mycetoma, like Leptosphaeria.
- Agents of black piedra, like Piedraia hortae.
3. Basidiomycetes– Mushrooms are the most commonly found basidiomycetes and mostly live as parasites. Sexual reproduction occurs by basidiospores. Asexual reproduction occurs by conidia, budding or fragmentation. Example- Agaricus.
Genera of medical importance include:
- Teleomorph of Cryptococcus neoformans, which is Filobasidiella neoformans.
- Agents of basidiomycosis such as Coprinus and Schizophyllium.
- Mushroom poisoning by Aminita, Lepiota, Coprinus Psilocybe etc.
4. Deuteromycetes– They are otherwise called imperfect fungi as they do not follow the regular reproduction cycle of the other fungi. They do not reproduce sexually. Asexual reproduction occurs by conidia. Example – Trichoderma.
There are three classes of imperfect fungi:
A. Blastomycetes- These include asexual budding forms of Cryptococcus, Candida, Torulopsis and Rhodotorula. Depending on the presence of melanin in their cell walls, they may be non-dematiaceous or dematiaceous.
B. Hyphomycetes- A class of mycelial moulds which reproduce asexually by conidia on hyphae. Hyphae are septate. This class contains the majority of medically important fungi. Dematiaceous hyphomycetes are conidial fungi that produce dark brown, green-black, or black colonies and are the causative agents of phaeohyphomycosis. Hyaline hyphomycetes include those conidial fungi, which are not darkly pigmented; colonies may be colourless or brightly coloured. These include the agents of hyalohyphomycosis, aspergillosis, dermatophytosis and dimorphic pathogens, like Histoplasma capsulatum.
C. Coelomycetes- These produce acervuli, which are tightly bound mats of hyphae on which conidia are produced.
Based on Morphology:
- Moulds (Molds)- Filamentous fungi E.g: Aspergillus sps, Trichophyton rubrum.
- Yeasts- Single-celled cells that bud E.g: Cryptococcus neoformans, Saccharomyces cerviciae.
- Yeast-like- Similar to yeasts but produces pseudohyphae Eg: Candida albicans.
- Dimorphic-Fungi exist in two different morphological forms at two different environmental conditions. They exist as yeasts in tissue and in vitro at 37 C and as moulds in their natural habitat and in vitro at room temperature. Eg: Histoplasma capsulatum, Blastomyces dermatidis, Paracoccidiodes brasiliensis, Coccidioides immitis.
Some 200 “human pathogens” have been recognized from among an estimated 1.5 million species of fungi.
Reproduction in Fungi
- Reproduction in fungi is both by sexual and asexual means. The sexual mode of reproduction is referred to as teleomorph (or perfect stage). and the asexual mode of reproduction is referred to as anamorph (or imperfect stage).
- Vegetative reproduction in fungi– This takes place by budding, fission and fragmentation.
- Asexual reproduction– This takes place with the help of spores called conidia zoospores, or sporangiospores.
- Sexual reproduction– This occurs in ascospores, basidiospores, and oospores. The conventional mode of sexual reproduction is not always observed in the kingdom of Fungi. In some fungi, the fusion of two haploid hyphae does not result in the formation of a diploid cell. In such cases, there appears an intermediate stage called the dikaryophase. This stage is followed by the formation of diploid cells.
References
- https://www.microrao.com/micronotes/mycology.pdf
- https://www.austincc.edu/ddingley/MLAB1331/LectureGuide/Mycology.pdf
- http://www.deskuenvis.nic.in/pdf/WEBSTER30521807395.pdf
- https://www.uobabylon.edu.iq/eprints/publication_1_13183_803.pdf
- https://www.scribd.com/document/8309461/Introduction-to-Mycology
- https://www.bpums.ac.ir/UploadedFiles/CourseFiles/2016_7_10/clinical_mycology__2eba2031d2.pdf
- https://www.kau.edu.sa/Files/0014257/Subjects/mycology%20terminologies.pdf
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