Introduction To Mycology PDF

INTRODUCTION TO MYCOLOGY  FUNGI  Constitute a large diverse group of organisms, most of them are found as saprophytes in the soil.  They are eukaryotic , their cell wall composed of chitin : polysaccharides (glucan & mannan). Their cell membrane contains Ergosterols (...

INTRODUCTION TO MYCOLOGY  FUNGI  Constitute a large diverse group of organisms, most of them are found as saprophytes in the soil.  They are eukaryotic , their cell wall composed of chitin : polysaccharides (glucan & mannan). Their cell membrane contains Ergosterols (resist to action of antibiotics.)  They show variation in size and forms but can be divided into three groups. Types of fungi  1.Moulds (filamentous fungi) They are similar to plants (plants without chlorophyll) they are divided into : a)Vegetate mycelium which is embedded in the medium like the root of the plant, it gives support &nutrition. b) Arial mycelium found above the substance of the medium resembles leaves, for growth and reproduction. E.g. moulds are Dermatophytes. Mycelium Types of fungi 2.Yeasts and yeast-like fungi: They are unicellular can be round, oval or elongated, some are capsulated (cryptococcus neoformans). Reproduces by budding , sometimes the daughter cell did not separate from the mother cell forming false hypha called psuehyphae (e.g. Candida sp.) Yeasts Types of fungi  3.Dimorphic fungi Can exist in the filamentous or the yeast form depending on the growth condition especially the temperature, in environment they are molds, but form yeasts in body temperature. e.g Histoplasma sp. Physiology of fungi 1.Oxegen : fungi are aerobes facultative anaerobes 2.Temprature: they grow in wide range of it between0-4°C are psychrophilic,14- 40°C are mesophilic, > 45°C are thermophilic. 3.Nutrition: they are heterotrophic, need organic N and C for their growth. 4.Reproduction:Some fungi reproduce sexually, some asexually or both. Classification of fungi  Depends on type of mycelium and mode of reproduction into: 1.Phycomycetes(zygomycetes) Known as water fungi, they are sapro- phytes but some causing opportunistic infections (phycomycosis)they reproduces by both asexually producing asexual spores (sporangiospores) or sexually producing zygospores.It had aseptated hyphae. Classification of fungi 2.Ascomycetes: Can be filamentous or yeast, it had a septated hyphae , the asexual spores are conidia, the sexual spores are the ascospores. 3.Basidomycetes: Of no medical importance except mushroom or some poisonous forms, the sexual spores are basidiospores. Classification of fungi 4.Deutromycetes: Called fungi imperfecta they had only one type of reproduction (asexually)but now both are found. they include medically important fungi, the filamentous, yeasts and dimorphic fungi They have septated hyphae. The asexual spores can be thallospores, conidia or sporangiospores. THANK YOU