Fungi. Pdf ..................................

....

1. FUNGI
•Fungiformadiversegroupofnon-motile,eukaryotic,
obligateorfacultativeaerobicorganismwhichexistas
saprophytes,parasites&commensals
•Theylackchlorophyllpigment,posesseddifferentiated
nucleisurroundedbynuclearmembraneand
reproduceeitherbybuddingorsporeorconidia
formation
•Theyposessrigidcellwallmadeupofchitin,mannan
&otherpolysaccharidesandtheircytoplasmic
membranecontainssterols
•FungiisidentifiedbyAugustinoBassi(1835)from
muscardinediseaseofsilkworm
•StudyisknownasMycology

2. CLASSIFICATIONOFFUNGI
Dependingoncellmorphology,fungicanbedividedinto4
classes:
I.Moulds
II.Yeasts
III.Yeast like fungi and
IV.Dimorphic fungi
Basedontheirsexualsporeformationfungiaredividedinto4
classes:
I.Zygomycetes
II.Ascomycetes
III.Basidiomycetes
IV.Dueteromycetes(Fungi imperfecti)

3. DEPENDING ON MORPHOLOGY OF CELL
1.MOLDS (filamentous/mycelialfungi)
•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 2-10μm .
•Hyphae continue to grow &branch to form tangled mass of growth
called mycelium
•The cell walls contain chitin.
•Some hyphaemay divided by cross sections called septa.
•Two types of hyphae: Septateand Non-septate
–I. Septate: septa divide the hyphaeinto distinct, uninucleateor
mulitnucleatecell-like units.
–II. Nonseptate/coenocytic: does not contain septa and appear as long,
continuous cells with many nuclei.
–Example: Dermatophytes, Aspergillus, Penicillium, Mucor, Rhizopus

5. 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%)
•Glucanand 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

7. 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

9. 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
mycelliumand 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: Blastomycesdermatitidis, Penicillium
marneffei

11. TAXONOMICAL CLASSIFICATION
1. ZYGOMYCETE'S
•Fungi having non-septatehyphae, 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 septatehyphae.
•Include both yeasts and filamentous fungi
•e.g. Histoplasm, Candida etc.
3. BASIDIOMYCETE'S
•Reproduce sexually and form septatehyphae.
•These basidiosporesare borne at the tip of the basidium
•Example: Cryptococcus neoformans
4. DEUTEROMYCETE’S
•Also called as Fungi Impefeciior Hyphomycetes.
•Consist of group of fungi whose sexual phases have not been identified and they form septate
hyphaeand asexual conidia.
•Majority of the pathogenic moulds, yeasts, yeasts like fungi and dimorphic fungi.
•Example: Trichophyton, Epidermophyton

12. 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 likehoodthat they
will be better suited for the environment.

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

14. 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:byfragmentation of the ends of hyphae
which results in production of rectangular or cuboidalthick
walled spores arthrospores
•Chlamydospores:thickwalled resting spores which develop
from hyphaeafter long dormancy, depending on
development in hyphaefrom which they grow they may be
–Intercalary –develop between 2 neighbouringsepta
–Lateral –develop on lateral hyphae
–Terminal-develop at the end of hyphae

16. 2. Aerial spores:
1.Conidiospores/conidia:Sporeswhich are borne
externally on sides or tips of special hypahe
Small in size, occur singly-microconidiaor
microaleuriospores
Larger size, multicellular,septate-
macroconidiaor macroaleuriospores
2. Phalospores:-modified conidia borne at tip of
flask shaped cpecialisedconidiophorecalled
phialide
3. sporangiospores : spores areformedwithin
thesaclike sporangium borne on the ends of
specialisedhyphae sporangiophore