1. Introduction to mycology

2. Fungi-Eucaryotes Eucaryotic cells with characteristic organelles
No chloroplasts
Thick cell wall, mostly carbohydrate
Cellulose or chitin most common components
Metabolically very similar, distinguished by morphology
3 main types
Yeasts
Filamentous fungi
Dimorphic fungi

3. Fungi
Yeasts
Mycelial fungi
Dimorphic fungi

4. Yeasts Unicellular fungi Grow by division
Budding
Binary fission
Some times daughter cells may not detach themselves the result is a pseudohyphae
Pseudohyphae

5. Filamentous fungi (molds)
Multicellular, multinucleate
Basic unit is the hyphae, a long thin filament
Hyphae branch and cross link to form a mat (mycelium)
Growth occurs at hyphal tip
Hyphae may be divided by cross-walls (septa) into uninuclear units
Non septate hyphae: coenocytic
Septa contain pore. All cytoplasm is connected.

6. Dimorphic fungi
Fungi able to switch between growth as a mycelium and a yeast
Depends on environmental conditions
Usually one form is pathogenic and the other is saprophytic
Most cases yeast form is pathogenic, eg, Histoplasma capsulatum
In some cases hyphal form is pathogenic, eg, Candida albicans

7. Dimorphic fungi: Candida albicans

8. Fungal spores: Vegetative spores
Arthrospores, eg, Coccidiodes immitis
Chlamydospores, eg, Candida albicans
Blastospores, eg, Candida albicans

9. Fungal spores: Asexual spores
Some hyphae grow up from the mycelium and differentiate to produce spores
The most important of these are conidiospores
The hyphae develops to produce a specialised spore producing body called the conidiophore
Some fungi produce large conidia containing multinucleate spores (macroconidia) and small conidia which produce unicellular spores

10. Conidiospores

11. Pathogenic mechanisms - Fungi
Invasiveness: multiply in skin and keratin producing common superficial infection (Ringworm, athletes foot)
Fungi gaining access to tissue cause subcutaneous infections
In the blood they cause life threatening systemic infections in the immunocompromised
Toxin production: ingestion of mouldy food in which fungal metabolites have been produced causes poisoning
Allergic reactions: inhalation of fungal hyphae or spores causes hypersensitivity reactions

12. Cultivation of fungi Fungi are chemoheterotrophs
Growth requirements similar to bacteria some require complex substances such as keratin
Optimum growth temperature for many fungi much lower than for pathogenic bacteria
Most fungi grow at lower pH than bacteria
Media
Sabourauds agar
Dextrose and peptone, pH5.6
Yeast grow as colonies
Filamentous fungi grow as a mycelium

13. Terminology
Ascospore: asexual spore produced in a sac-like structure called an ascus
Arthospores: asexual spore formed by the disarticulation of the mycelium
Blastospores are formed by budding from the ends or sides of the parent cell, e.g., the yeast, Candida
Chlamydospores: thick-walled, resistant spores formed by the direct differentiation of hyphae
Conidia: asexual spore formed from hyphae by budding or septal division

14. Terminology
Conidiophore: a stalk-like branch from the mycelium in which conidia develop either singly or in numbers
Germ tubes: tube-like structures produced by germinating spores
Hyphae: the filaments that composed the body of a fungus
Macroconidia: large multinucleate spores
Microconidia: single-celled spores
Mycelium: a mat made up of interwining thread-like hyphae
Pseudohyphae: filaments composed of elongated budding cells that have failed to detach