Mary Cole; Week 12 MED1011; Microbiology
Fungi are divided into 3 kingdoms; Protoctista = Chromista + Protozoa + Eumycota. Most are soil inhabitants. Optimum growth is 20 to 30 degrees. Some are thermophilic, most can be dormant in very low temperatures. Prefer acid medium around 6pH. Light is not required for growth but is required for some to sporulate. Spore > germ tube > hypha > mycelium > fungal thallus. Hyphae (strands) can be non-septate or septate, mycelium is mat of hyphae, yeast form is from single cells. Can reproduce asexually or sexually. Two types of asexual reproduction: primitive is sporangia enclosing sporangiospores, complex is conidia or conidiophores. Can occur many times a season. Sexual reproduction generally occurs once a season. Has 3 phases: plasmogamy brings 2 haploid nuclei together in one cell, karyogamy unites to form diploid nucleus, meiosis restores the haploid state. Some fungi are monoecious (homothalic) with both sets of sex organs, diecious (heterothallic) have sex organs on two different individuals.
Fungi rely on carbon, can be parasitic, symbiotic or saprophytes (use dead material for nutrition). They need enzymes to degrade difficult materials. All fungi need nitrogen, use enzymes when preferred form is not available.
Zygomycota is bread mold. Rarely causes disease. Chytridiomycota causes frog disease. Ascomycotina have filamentous forms with septate hyphae and yeast forms, can cause food spoilage, includes truffles and most yeasts. Basidiomycotina is colourful mushrooms. Anamorphici only have asexual stage known, are classified when sexual stages are discovered.
Fungi have 80S ribosomes (bacteria have 70S). Usually cause fungal allergies, mycotoxins (toxicoses) and infections (mycosis) which can be primary, opportunistic, cutaneous and subcutaneous. Treat fungal allergies with immunotherapy. Fungal toxins are treated with antibiotics, are harmful to humans. Mycotoxins can cause resp distress, burning in throat and lungs, headaches, memory loss and swollen lymph nodes. Cutaneous fungal diseases can be ringworm, tinea and thrush. Subcutaneous can also occur. Systemic mycoses are life threatening, common in hot climates. Opportunistic mycoses are commonly Candida. Aspergillosis is farmer's lung, breathed through bronchial system and there are 3 types- allergic (hypersensitive), aggressive tissue invasion (invades pulmonary then other organs), fungus ball (mass in pre existing lung cavities eg TB patients, lung scar, abscess).