Fungi

• The study of fungi encompasses various aspects, including their morphology, classification, reproduction/replication, and cultivation.

Morphology of Fungi

Morphology of Fungi

Structure:

1. 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).

2. Mycelium: A network of hyphae that forms the body (thallus) of the fungus. The mycelium is responsible for nutrient absorption.

3. Spores: Reproductive units that can be asexual (conidia, sporangiospores) or sexual (ascospores, basidiospores).

4. Fruiting Bodies: Specialized structures like mushrooms, which produce and release spores.

Cellular Organization:

1. Cell Wall: Composed mainly of chitin, glucans, and sometimes cellulose.

2. Cell Membrane: Contains ergosterol, different from cholesterol found in animal cells.

3. 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:

Fungal Phyla

1. Zygomycota (Zygomycetes): Known for zygospores formed during sexual reproduction. Example: Rhizopus (bread mold).

2. Ascomycota (Sac Fungi): Produce spores in sac-like structures called asci. Includes yeasts and molds. Example: Saccharomyces cerevisiae (baker's yeast).

3. Basidiomycota (Club Fungi): Produce spores on club-shaped structures called basidia. Includes mushrooms and toadstools. Example: Agaricus bisporus (common mushroom).

4. Deuteromycota (Imperfect Fungi): Fungi for which only asexual reproduction is known (e.g., Penicillium).

Fungal Forms:

1. Yeasts: Unicellular fungi that reproduce by budding or fission.

2. Molds: Multicellular fungi with filamentous hyphae.

Reproduction/Replication of Fungi

Asexual Reproduction:

1. Budding: Common in yeasts, where a new cell grows out of the body of a parent.

2. Fission: Simple cell division in unicellular fungi.

3. Spore Formation: Asexual spores (conidia, sporangiospores) are produced by mitosis and dispersed to form new individuals.

Sexual Reproduction:

1. Plasmogamy: Fusion of cytoplasm from two parent mycelia.

2. Karyogamy: Fusion of nuclei from two parent mycelia.

3. Meiosis: Reductional division to produce sexual spores (ascospores, basidiospores).

4. Spore Dispersal: Spores are released into the environment to germinate into new mycelia.

Cultivation of Fungi

Environmental Conditions:

1. Temperature: Most fungi grow well at 20-30°C, though some can tolerate extremes.

2. pH: Optimal pH for most fungi is slightly acidic (pH 4-6).

3. Moisture: High humidity is generally favorable for fungal growth.

4. Nutrients: Fungi require organic matter, nitrogen, vitamins, and minerals.

Culture Media:

1. Potato Dextrose Agar (PDA): Common medium for general cultivation.

2. Sabouraud Dextrose Agar (SDA): Used for fungi with acidic tolerance.

3. Malt Extract Agar (MEA): Rich in nutrients for fastidious fungi.

Techniques:

1. Inoculation: Introducing fungal spores or mycelium to the culture medium.

2. Incubation: Maintaining the culture under suitable environmental conditions.

3. Isolation: Obtaining pure cultures by subculturing from a mixed population.