fungi...............................pptx

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1. FUNGI Fungi form a diverse group of non-motile, eukaryotic, obligate or facultative aerobic organism which exist as saprophytes,parasites & commensals They lack chlorophyll pigment,posessed differentiated nuclei surrounded by nuclear membrane and reproduce either by budding or spore or conidia formation They posess rigid cellwall made up of chitin,mannan &other polysaccharides and their cytoplasmic membrane contains sterols Fungi is identified by Augustino Bassi (1835) from muscardine disease of silkworm Study is known as Mycology

2. CLASSIFICATION OF FUNGI Depending on cell morphology, fungi can be divided into 4 classes: Moulds Yeasts Yeast like fungi and Dimorphic fungi Based on their sexual spore formation fungi are divided into 4 classes: Zygomycetes Ascomycetes Basidiomycetes Dueteromycetes (Fungi imperfecti )

3. DEPENDING ON MORPHOLOGY OF CELL MOLDS (filamentous/ mycelial fungi) Fungi which form true mycelium and grow as branching Filaments are called hyphae . They produce different types of sexual and asexual spores which germinate to produce hyphae with Diameter 2-10 μ m . Hyphae continue to grow &branch to form tangled mass of growth called mycelium The cell walls contain chitin. Some hyphae may divided by cross sections called septa. Two types of hyphae : Septate and Non- septate I. Septate : septa divide the hyphae into distinct, uninucleate or mulitnucleate cell-like units. II. Nonseptate / coenocytic : does not contain septa and appear as long, continuous cells with many nuclei. Example: Dermatophytes , Aspergillus , Penicillium , Mucor , Rhizopus

4. 2. YEASTS Round, oval or elongated, unicellular fungi Reproduce by an asexual process called budding in which the cell develops a protuberance which enlarges and eventually separates from the parent cell On culture they form smooth, creamy colonies Example: Saccharomyces cerevisae , Cryptococcus neoformans Contains Granular cytoplasm enclosed in cell wall. Consist oil globule, vacuole, cytoplasm, glycogen and prominent nucleus and nucleolus Cell wall composed of – Chitin, (1-10%) Glucan (main structural component 50-60%), Lipid-Protein (15-23%) Glucan and Chitin regulate cell division and cell rigidity Mode of nutrients- Heterotroph , Organotroph , Saprophytic ,Parasitic Grow best in acidic environment and can tolerate high sugar concentration and dry condition

5. 3. YEAST LIKE FUNGI Unicellular (Rounded or Oval) Chain of elongated budding cell which are joined end to end forming pseudomycelium The bud remains attached to the mother cell and elongates, followed by repeated budding, forming chains of elongated chains known as pseudohyphae . Example: Candida albicans

6. 4. DIMORPHIC FUNGI Mainly pathogenic species exhibit dimorphism i.e. 2 forms of growth Fungi can grow either as a mould or as a yeast Mould like forms produce vegetative and aerial mycellium and Yeast like forms reproduce by budding Dimorphism is temperature and CO2 dependant. At 37oC, the fungus grows yeast like and at 25oC it shows mould like growth Example: Blastomyces dermatitidis , Penicillium marneffei

7. TAXONOMICAL CLASSIFICATION 1. ZYGOMYCETE'S Fungi having non- septate hyphae , forms endogenous asexual spores ( sporangiospores ) contained within a sac like structures called sporangia. Also produce sexual spores known as oospores and zygospores .  Example: Mucor , Rhizopus . 2. ASCOMYCETE’S Form sexual spores within a sac and are called ascospores . The sac is called as ascus . They form septate hyphae . Include both yeasts and filamentous fungi e.g. Histoplasm , Candida etc. 3. BASIDIOMYCETE'S Reproduce sexually and form septate hyphae . These basidiospores are borne at the tip of the basidium Example: Cryptococcus neoformans 4. DEUTEROMYCETE’S Also called as Fungi Impefecii or Hyphomycetes . Consist of group of fungi whose sexual phases have not been identified and they form septate hyphae and asexual conidia. Majority of the pathogenic moulds, yeasts, yeasts like fungi and dimorphic fungi.  Example: Trichophyton , Epidermophyton

8. REPRODUCTION Most fungi reproduce both sexually and asexually. When environmental conditions are favorable, asexual reproduction occurs rapidly. When unfavorable conditions stress the organism, sexual reproduction occurs and the offspring have an increased likehood that they will be better suited for the environment.

9. 1.SEXUAL Occurs fusion of 2 different cell( male&female ) is called Plasmogamy followed by fusion of two nuclei is Karyogamy Zygote is developed as a result of sexual spores which may be oospores, zygospores,ascospores,and basidiospores All these type of spores are formed in higher fungi with least medical imp

10. ASEXUAL Medically imp fungi are reproduce by this method They produce different asexual spores by mitosis which may be vegetative or aerial spores 1.Vegetative spores Blastospores : formed by budding process from parent cells as in the yeast Arthrospores:by fragmentation of the ends of hyphae which results in production of rectangular or cuboidal thick walled spores arthrospores Chlamydospores:thick walled resting spores which develop from hyphae after long dormancy, depending on development in hyphae from which they grow they may be Intercalary –develop between 2 neighbouring septa Lateral – develop on lateral hyphae Terminal- develop at the end of hyphae

11. 2. Aerial spores: 1.Conidiospores/ conidia:Spores which are borne externally on sides or tips of special hypahe Small in size, occur singly- microconidia or microaleuriospores Larger size, multicellular,septate-macroconidia or macroaleuriospores 2. Phalospores :- modified conidia borne at tip of flask shaped cpecialised conidiophore called phialide 3. sporangiospores : spores areformed within thesac like sporangium borne on the ends of specialised hyphae sporangiophore