Mycology Lec.1 Dr. Manahil

Mycology is the study of fungi, which is branch of biology. Approximately 80,000 species of fungi have been described. The main characteristics of fungi. They are an important component in the energy cycle. They are eukaryotic organisms that do not contain chlorophyll, with cell wall containing chitin .

They are aerobic, have chemohetrophic type of nutrition. Some fungi are small in size ( about 3µ. in diam.) where as others are large and can be seen by the naked eye. Extra enzyme Insoluble polymer Fungi absorb Soluble organic materials

They have no organic level differentiation. The cell membrane contains sterols. Moisture is necessary for the growth of molds and yeasts, they prefer moderate temp. All fungi need a protein source and carbohydrate source. Fungi are able to tolerate a wide rang of PH, many of them can grow in medium that have a PH 2-10, although they prefer a neutral PH.

They may be unicellular or multicellular. Yeasts are generally unicellular and produce circular restricted pasty or mucoid colonies. Molds are multicelled filamentous forms of fungi consisting of thread like filaments termed hyphae. septate hyphae hypha aseptate

alcoholic fermentation. preparation of certain cheeses. Many of the fungal pathogen are dimorphic or diphasic, with a yeast (Y) and a mycelial (M) phase. 11. Many fungi are responsible for much of the disintegration of organic matter and they affect us directly by destroying food, fabrics, leathers and other consumer. Other fungi are beneficial which are the basis of a number of industrial processes involving: Fermentation such as making of bread. alcoholic fermentation. preparation of certain cheeses. Production of many organic acids. Responsible for the manufacture of a number of antibiotic drugs as penicillin which is produced by penicillium M 30°C Y 37°C

Some cause diseases in plants, animal and harm man more directly. There are four type of mycotic diseases: Hypersensitivity. Mycotoxicoses. Mycetismus. Infection: pathogenic fungi do not produce toxins but they show physiologic modifications during a parasitic infection

Classification of fungi: There are four (4) important classes of medically important fungi class Zygomycetes (lower fungi). class Ascomycetes Telomorphic or class Basidiomycetes perfect fungi. class Deutromycetes anamorphic or imperfect fungi Fungi in class Zygomycetes have wide mycelium. Nuclei In Ascomycetes, Basidiomycetes and Deutromycetes, the mycelium is less than 5µ. in diam and it is septated

Reproduction of fungi Fungi reproduce by spores either sexually or asexually. The spore is a resistant unit of fungi. Sexual reproduction involve three (3) processes Plasmogamy i.e. fusion of protoplasm of (2) sex cells to form a pigmass. Karyogamy i.e. fusion of (2) nuclei to form one mass. Meosis i.e. reduction division.

Resting Sexual reproduction in Zygomycetes Plasmogamy Karyogamy Meosis + - Exp: Rhizopus, Mucor 4 Zygospores. Resting Sexual reproduction in Ascomycetes Resting Plasmogamy Karyogamy Meosis Ascospores (endogenous) ascus 4 Ascospores mitosis 8 Ascospores (inside ascus) Sexual reproduction in Basidiomycetes resting plasmogamy Karyogamy Meosis Basidium Basidiospores 4 basidiospores (exogenous) EX.P: Mushroom

Deutromycetes have no sexual reproduction only asexual form Asexual spores The morphology, arrangement and mode of derivation of spores serve as important criteria by which genus and species identification can be made Sporangiospores: EX. P: Rhizopus Sporangiospores Sporangium Sporangiophores 2. Arthrospores (arthroconidia): They formed due to fragmentation of the mycelium EX.P: Geotrichum, Trichosporon

3. Blastospores (Blastoconidia): Produce by budding and separation from the parent cell + EX.P: Candida 4. Chlamydospores (chlamydoconidia): Terminal Intercalary

conidia either unicellular (microconidia) or multicellular 5. Conidia: Usually produced terminally or laterally on hyphae or special structure, conidiophores, and are borne externally as a single cell. conidia either unicellular (microconidia) or multicellular (macroconidia) EX.P: penicillium, Dermatophytes. unicellular multicellular