The study of fungi encompasses various aspects, including their morphology, classification, reproduction/replication, and cultivation.
Morphology of Fungi
Structure:
Hyphae: The basic structural units of fungi, which are long, thread-like filaments. They can be septate (divided by cross walls) or coenocytic (without septa).
Mycelium: A network of hyphae that forms the body (thallus) of the fungus. The mycelium is responsible for nutrient absorption.
Spores: Reproductive units that can be asexual (conidia, sporangiospores) or sexual (ascospores, basidiospores).
Fruiting Bodies: Specialized structures like mushrooms, which produce and release spores.
Cellular Organization:
Cell Wall: Composed mainly of chitin, glucans, and sometimes cellulose.
Cell Membrane: Contains ergosterol, different from cholesterol found in animal cells.
Organelles: Includes a nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, and sometimes vacuoles.
Classification
Kingdom Fungi:
Fungi are classified based on their reproductive structures and methods, molecular data, and other morphological features.
Major Phyla:
Zygomycota (Zygomycetes): Known for zygospores formed during sexual reproduction. Example: Rhizopus (bread mold).
Ascomycota (Sac Fungi): Produce spores in sac-like structures called asci. Includes yeasts and molds. Example: Saccharomyces cerevisiae (baker's yeast).
Basidiomycota (Club Fungi): Produce spores on club-shaped structures called basidia. Includes mushrooms and toadstools. Example: Agaricus bisporus (common mushroom).
Deuteromycota (Imperfect Fungi): Fungi for which only asexual reproduction is known (e.g., Penicillium).
Fungal Forms:
Yeasts: Unicellular fungi that reproduce by budding or fission.
Molds: Multicellular fungi with filamentous hyphae.
Reproduction/Replication of Fungi
Asexual Reproduction:
Budding: Common in yeasts, where a new cell grows out of the body of a parent.
Fission: Simple cell division in unicellular fungi.
Spore Formation: Asexual spores (conidia, sporangiospores) are produced by mitosis and dispersed to form new individuals.
Sexual Reproduction:
Plasmogamy: Fusion of cytoplasm from two parent mycelia.
Karyogamy: Fusion of nuclei from two parent mycelia.
Meiosis: Reductional division to produce sexual spores (ascospores, basidiospores).
Spore Dispersal: Spores are released into the environment to germinate into new mycelia.
Cultivation of Fungi
Environmental Conditions:
Temperature: Most fungi grow well at 20-30°C, though some can tolerate extremes.
pH: Optimal pH for most fungi is slightly acidic (pH 4-6).
Moisture: High humidity is generally favorable for fungal growth.
Nutrients: Fungi require organic matter, nitrogen, vitamins, and minerals.
Culture Media:
Potato Dextrose Agar (PDA): Common medium for general cultivation.
Sabouraud Dextrose Agar (SDA): Used for fungi with acidic tolerance.
Malt Extract Agar (MEA): Rich in nutrients for fastidious fungi.
Techniques:
Inoculation: Introducing fungal spores or mycelium to the culture medium.
Incubation: Maintaining the culture under suitable environmental conditions.
Isolation: Obtaining pure cultures by subculturing from a mixed population.