Fungi Mycology Avascular typically not motile Aerobes or

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

Aspergillus niger

• 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 yeasts reproduce asexually through budding – Form psudo-hyphae – Saccharomyces • Fission yeasts divide 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