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Fungi. Mycology Avascular, typically not motile Aerobes or facultative anaerobes Chemoorganoheterotrophs Many are saprophytes Some are parasites. Cell walls similar in structure to plants but vary in chemical composition Chitin, glucan, mannan Thallus (body)
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Fungi • Mycology • Avascular, typically not motile • Aerobes or facultative anaerobes • Chemoorganoheterotrophs • Many are saprophytes • Some are parasites
Cell walls similar in structure to plants but vary in chemical composition • Chitin, glucan, mannan • Thallus (body) • unicellular (yeasts) or multi-cellular (molds) • Mycelium (molds) • loosely organized mass of filamentous hyphae
Dimorphic Fungi • Most serious fungal pathogens • Grow as yeast or mold • Depends on environmental conditions
Fungi typically reproduce by means of spores • sexual (meiotic) and asexual (mitotic) spores may be produced • asexual fragmentation may occur
Spores are typically released from aerial hyphae in molds • Vegetative hyphae are involved in nutrient absorption
Asexual spores • Typically wind dispersed • Commonly used to identify fungal pathogens • Two types of asexual spores: • Sporangiospore (inside sporangium sac) • Conidiospore (Various forms, not formed in a sac)
Conidiospores Coccidioides Aspergillus Crypotococcus
Sporangiospores Rhizopus
Most yeastsreproduce asexually through budding • Form psudo-hyphae • Saccharomyces • Fission yeastsdivide evenly to produce two cells • Schizosaccharomyces
Fungi classified into divisions (phyla) according to sexual reproductive process: • Chytridiomycota (primitive fungi) • Zygomycota (conjugation fungi) • Ascomycota (sac fungi) • Basidiomycota (club fungi) • Deuteromycota (imperfect fungi) • anamorphic fungi
Pathogenic Fungi • Stachybotrys • the spores are inhaled causing serious forms of hemorrhagic pneumonia • Produce several toxic chemicals called mycotoxins • Aspergillus • commonly grows as “mildew” in shower • can cause opportunistic infections • Inhaled soil spores can cause Aspergillosis
Pneumocystis • severe pneumonia in AIDS patients • Candida albicans • Causes skin level fungal infections of the mouth (oral thrush), groin (diaper rash), and the vagina (candida vaginitis) or “yeast infection” • Dimorphic fungi that can cause serious systemic mycoses
Cryptococcus neoformans • cryptococcosis, one of the most serious fungal diseases worldwide • major manifestation is meningoencephalitis • has become increasingly important with the AIDS epidemic
Beneficial fungi • Fungi decomposers in food webs • Most plants require association with Mycorrhizae • Many fungi are a source of food
Saccharomyces • Fermentation of bread and alcoholic beverages • Torulopsis • protein supplements for humans and cattle • Aspergillus • produce citric acid for food and beverages • Trichoderma • fruit juice production