Fungi Lecture Notes PDF

Fungi Fungus: is a Latin name means Mushroom Mycology: is a discipline of biology which deals with the study of fungi. Mycology studies Structure, Reproduction, Physiology & Taxonomy of fungi General Characters of Fungi I. Habitat II. Mode of Life “Nutrition”...

Fungi Fungus: is a Latin name means Mushroom Mycology: is a discipline of biology which deals with the study of fungi. Mycology studies Structure, Reproduction, Physiology & Taxonomy of fungi General Characters of Fungi I. Habitat II. Mode of Life “Nutrition” III. Structure IV. Reproduction V. Classification  I. Habitat Fungi are widely distributed in almost every habitat where organic material is present. They may be: 1. Terrestrial, 2. Aquatic, 3. Pathogenic, Or 4. Contaminants.  1. Terrestrial 2. Aquatic Fungi Fungi live in soil (Advanced Live on decaying organic Fungi) matter or living organisms Produce non- motile in fresh water. reproductive cells Produce motile dispersed by wind, water reproductive cells which or animals. swim to new places 3. Pathogenic 4. Contaminant Fungi Fungi Live in living animal or Found in Air, Food or plant tissues causing drinking water. disease.  II. Mode of Life “Nutrition” Fungi are Heterotrophic , they lack Chlorophyll, so they obtain food ready made by absorption from external sources. They may be: 1. Saprophytic, 2. Parasitic, Or 3. Symbiotic  1. Saprophytic Fungi “They live on dead organic matter” a. Obligate Saprophytes b. Facultative Saprophytes They live only Normally they live as Saprophytes. parasites and they able to They are incapable of grow saprophytes in certain infecting plants or animals conditions.  2. Parasitic Fungi “They may live on (Ectoparasites) or inside (Endoparasites) living organisms and obtain their food from them causing disease” a. Obligate Parasites b. Facultative Parasites They live only in suitable Normally they live as living host tissue. saprophytes and they may become parasites in certain conditions.  3. Symbiotic Fungi “They live in association with other organisms” e.g. Mycorrhiza Fungi: absorb water and mineral from the soil Tree: provides food to the fungus.  III. Structure of Fungi Fungi are Eukaryotic contain true nucleus. They contain cell wall formed of glucans and chitin. They may be: 1.Unicellular. Or 2. Multicellular.  1. Unicellular 2. Multicellular Fungi Fungi They are more or less a. Aseptated Mycelium spherical single cells. Lack internal partitions e.g. e.g. Saccharomyces Rhizopus a. Septated Mycelium contain internal cross walls at regular intervals e.g. Penicellium  IV. Reproduction of Fungi Fungi reproduce by 1. Asexual Reproduction. Or 2. Sexual Reproduction.  1. Asexual 2. Sexual Reproduction Reproduction Does not involve the union Characterized by the union of nuclei, sex cells or sex of two nuclei. organelles. It may occur by: It consists of 3 phases: a. Fragmentation a. Plasmogamy b. Fission b. Karyogamy c. Budding c. Meiosis d. Spore Formation  1. Asexual Reproduction a. Fragmentation: Hyphae break up into their component cells. b. Fission: Splitting of a cell into 2 cells by constriction and formation of a cell wall.  1. Asexual Reproduction c. Budding: Production of outgrowth(bud) from a parent cell. Chains of bud may form short mycelium. c. Spore Formation: Sporangiospores: formed within a sporangium e.g. Rhizopus Conidiospores: produced at the tips of hyphae e.g. Penicellium  1. Sexual Reproduction a. Plasmogamy: Union of 2 plasmoplasts. a. Karyogamy: The fusion of 2 nuclei into one diploid nucleus. a. Meiosis: Division of the diploid nucleus To reduce the number of chromosomes to the haploid number.  V. Classification of Fungi Based on the spore case in which the spores are produced fungi are classified into four divisions: 1. Zygomycota: Zygote forming Fungi (Zygospores) 2. Ascomycota: Sac Fungi (Ascospores) 3. Basidiomycota: Club Fungi (Basidiospores)  1. Division Zygomycota: They are zygote forming fungi. The Zygospores are produced in round-shaped case called sporangium. The grayish fuzz seen on bread and decaying food is actually mass of mature sporangia mold. When the sporangium breaks open hundreds of spores are released. Example: Mucor, Rhizopus (Bread mold) and Albugo.  Example of Zygomycota Rhizopus * Classification Kingdom : Fungi Division : Zygomycota Genus : Rhizopus Rhizopus life cycle  2. Division Ascomycota: The sac-fungi produce Ascospores in small cup-shaped sacs called asci, hence the name Ascomycota. The Ascospores released at the tip of the ascus breaks open. Yeast is the most common one-celled fungi. Yeast reproduces through asexual process called budding. Examples of sac-fungi are morels, truffles, cup fungi and powdery mildews. Example: Aspergillus Examples of Ascomycota Aspergillus *Classification: Kingdom: Fungi Division: Ascomycota Genus: Aspergillus Examples of Ascomycota Penicellium *Classification: Kingdom: Fungi Division: Ascomycota Genus: Penicellium  3. Division Basidiomycota: The Basidiospores are borne on a club-shaped spore case called basidium. Basidiomycota includes the mushrooms, puff-balls, and toadstools. In mushrooms the basidia are lined at the gills under the cap. In fact, an average sized mushroom produces over 16 billion spores. These spores rarely germinate or mature. Example: Agaricus (mushroom), Ustilago (smut), and Puccinia (rust fungus). Example of Basidiomycota Agaricus sp. *Classification: Kingdom: Fungi Phylum: Basidiomycota Genus: Agaricus Agaricus life cycle  VI. Importance of Fungi Useful Fungi : are important in a variety of ways: 1. Recycling : Together with bacteria , Fungi form a major role in recycling the dead and decayed matter. 2. Edible Fungi: Many mushrooms are used as food by humans. Mushrooms species are edible and are cultured in many parts of the world for sale. 3. Medicines: Many fungi produce antibiotics, which are used to control diseases in humans and animals. Penicillin (antibiotic) is derived from a common fungi Penicillium. 4. Bio-control Agents: Fungi are used to parasitise insects which help control pests. Spores of fungi are sprayed on crops, this method is cheaper and environmentally friendly. Harmful Fungi: 1. Food spoilage: Fungal damage is responsible for large losses of stored food usually when the food contains moisture. Example: Toxins (Aflatoxins) produced by fungi that grow in or on certain foods (Peanuts). These natural contaminants are dangerous to both humans and animals and linked to cancer and death when ingested in large amounts. Harmful Fungi: 2. Plant and Animal Diseases: Many fungi live on and in plants and animals causing diseases. Examples of Plant Diseases: a) Powdery mildews. b) Rusts. Superficial Mycoses: The important superficial mycosis includes: * Ringworm (dermatophytosis), caused by Microsporum species * Pityriasis versicolor (tinea versicolor). Dermatophyte Infections: The dermatophytes are fungi that colonize skin, hair, and nails on the living host. These fungi possess greater invasive properties than those causing superficial infections, but they are limited to the keratinized tissues. They cause a wide spectrum of diseases that range from a mild scaling disorder to one that is generalized and highly inflammatory.