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1. INTRODUCTION TO
MYCOLOGY

3. What is a Fungus ?
• Eukaryotic - a true nucleus
• Do not contain chlorophyll
• Have cell walls
• Produce filamentous structures
• Produce spores
• Grow as saprophytes and decompose dead organic matter

4. Species of Fungi
• 100,000 – 200,000 species
• About 300 pathogenic for man

5. • Fungal Cell wall consists primarily of chitin (not
peptidoglycan)
• insensitive to antibiotics (penicillin)
• Fungal cell membrane contains ergosterol and
zymosterol (human cell membrane contain
cholesterol).
• the selective action of antifungal drugs is based on
the difference in membrane sterols.
Two fungal cell strctrues are
important medically

6. Feature Fungi Bacteria
Diameter Approximately 4 μm
(Candida)
Approximately 1 μm
(Staphylococcus)
Nucleus Eukaryotic Prokaryotic
Cytoplasm Mitochondria and
endoplasmic reticulum
present
Mitochondria and
endoplasmic
reticulum absent
Cell membrane Sterols present Sterols absent
Cell wall content Chitin Peptidoglycan
Spores Sexual and asexual spores Endospores for
survival
Thermal
dimorphism
Yes No
Metabolism Require organic carbon; no
obligate anaerobes
Many do not requires
organic carbon;
Comparison of fungi and bacteria

7. Features of Fungi and its value in our life:
The fungi are diverse organisms, that degrade organic matter.
Fungi have heterotrophic life; they could survive in nature as:
Saprophytic: live on dead or decaying matter
Symbiotic: live together and have mutual advantage
Commensal: one benefits and other neither benefits nor
harmed.
Parasitic: live on or within a host, they get benefit and harm the
other.
Fungi mainly infect immunocompromised or hospitalized patients
with serious underlying diseases.
The list of opportunistic fungal pathogens likewise increases each
year “It seems there are no non-pathogenic fungi anymore ! “
This increase in fungal infections can be attributed to the ever-
growing number of immunocompromised patients.

8. Moulds are multicellular organisms consisting of threadlike
tubular structures called Hyphae that elongate by apical
extension.
Hyphae are either:
Coenocytic: hollow and multinucleate
Septate: divided by partitions or cross-walls
Hyphae form together to produce a mat-like structure
called a Mycelium.
Vegetative hyphae, grow on or under surface of culture
medium,
Aerial Hyphae: project above surface of medium
Many medical fungi are termed dimorphic because they exist
in yeast and mould forms.

9. Characteristics of fungi
A. eukaryotic, non- vascular organisms
B.reproduce by means of spores (conidia), usually wind-
disseminated
C.both sexual (meiotic) and asexual (mitotic) spores may be
produced, depending on the species and conditions
D.typically not motile, although a few (e.g. Chytrids) have a motile
phase.
E. like plants, may have a stable haploid & diploid states
F. vegetative body may be unicellular (yeasts) or multicellular
moulds composed of microscopic threads called hyphae.
G. cell walls composed of mostly of chitin and glucan.

10. More Characteristics of Fungi
H. fungi are heterotrophic ( “other feeding,” must feed on
preformed organic material), not autotrophic ( “self feeding,”
make their own food by photosynthesis.
I. Most fungi store their food as glycogen (like animals). Plants
store food as starch.
K. Fungal cell membranes have a unique sterol, ergosterol, which
replaces cholesterol found in mammalian cell membranes
L. Tubule protein—production of a different type in microtubules
formed during nuclear division.

11. Fungi
Yeast
(single cells)
Asexual budding
spore
Hyphae (mycelium)
Mold
Morphology

12. Structure
•The body of fungi is termed thallus (non-
reproductive)
•The thalli of yeast are small, globular and are single
celled
•The thalli of mold are composed of long, branched
tubular filaments called hyphae.

13. Fungal Morphology
Yeast
Hyphae(threads)
makingupa mycelium
Mould
Encapsulatedyeast
Cryptococcus neoformans

14. Classification of fungi
They are classified by several methods:
1- Morphological classification
2 Systematic classification
3 Clinical classification

15. CLASSIFICATION
• Depending on cell
morphology
1.Yeasts
2.Yeast like fungi
3.Molds
4.Dimorphic fungi

17. Yeast like fungi
• Grow partly as yeasts and partly as
elongated cells resembling hyphae
which are called pseudo hyphae.
e.g. Candida albicans

19. Dimorphic Fungi
• Growth as a mold or as a yeast
• Most pathogenic fungi are dimorphic fungi
• At 37oC yeast-like
• At 25oC mold-like
• Can also occur with changes in CO2
• Fungi grow differently in tissue vs
nature/culture; often dictated by temp

20. • Some fungi are
dimorphic
depending on
environmental
conditions
These organisms
produce both
yeast-like and
mold-like thalli
Many are
pathogenic
•
•
• Candida albicans
Dimorphism
Figure 12.4

21. Dimorphism
Manypathogenicfungiaredimorphic , forming
mouldsatambienttemperaturesbutyeastsat
body temperature.

22. Reproduction in fungi
• Sexual - formation of Zygospore,
ascospores or basidiospores
• Asexual reproduction –
budding or fission
• Asexual spores are formed on or in
specialized structures.
• Vary in size, shape & colour but these
characteristics are constant for a
particular species.

23. Spores
• Some fungi reproduce sexually by mating and forming sexual
spores.
• Most fungi of medical interest propagate asexually by forming
asexual spores from the sides or ends of mycelim.
• The shape, color, and arrangement of asexual spores aid in the
identification of fungi.

24. Systematic classification
• Based on sexual spore
formation: 4 classes
1. Zygomycetes
2. Ascomycetes
3. Basidiomycetes
4. Deuteromycetes (fungi
imperfectii)

25. Zygomycetes
• Lower fungi
• Broad,
nonseptate
hyphae
• Asexual spores -
Sporangiospores:
present within a
swollen sac- like
structure called
Sporangium

26. Zygomycetes
• Sexual spores -
Zygospore: a
resting, thick
walled cell in
between hyphae
e.g.
Rhizopus,
Mucor

27. Ascomycetes
• Includes both yeasts & filamentous fungi
• Narrow, septate hyphae
• Asexual spores are called conidia
borne on conidiophore

28. Ascomycetes
• Sexual spores called
ascospores are
present within a sac
like structure called
Ascus.
• Several asci may be
seen within a fruiting
body as seen in
Penicillium,
Aspergillus
• Each ascus has 4
to 8 ascospores.

29. Basidiomycetes
• Sexual fusion results in the formation of
a club shaped organ called base or
basidium which bear
spores called basidiospores

30. Deuteromycetes or
Fungi imperfectii
• Group of fungi whose
sexual phases are not
identified.
• Grow as molds as well as
yeasts.
• Asexual stage – conidia
e.g. Candida, Cryptococcus

31. Asexual
Spores
• Produced by aerial hyphae: adapted for
dispersal
• Progeny genetically identical to parent
• Several types
– Conidiospores- not enclosed in a sac
• produced in a chain at end of a conidiophore
• Several types
– Sporangiospores
• Within a sac, sporangium
• End of sporangiophore

33. asexual
spores
sporangiospore
Conidia
microconidium
macrconidium
arthrospore
chlamydospore
blastospore
thallospore

34. asexual spores
• Arthrospores
- Arise by fragmentation of the ends of hypae
• Chlamydospores
- Rounded, thick-walled, quite resistant

35. asexual spores
• Blastospores
- Formed by the budding process
• Sporangiospores
- Formed within a sac on a stalk by molds

36. Some shapes of hyphae

37. C albicans form multiple buds that do not detach,
producing sausagelike chains
↓
↓
Pseudohyphae
Visually resemble hyphae but are not true hyphae

38. Classification on the base of disease
1. Superficially Mycose
• This type of fungi cause superficial infection.
• It effects skin, hair, nails mucosa.
• Example:
• Dermatophytosis

39. 2. Subcutaneous Mycose
• This type of fungi are transmitted by soil and it is mainly effect tissue.
• Habitat: Soil, Feaces
• Example:
• Mycetoma

40. 3. Systemic Mycose
• It transmit by inhalation process
• It is mainly effect internal part of body as CNS, Heart, Bones ets
• Examples
• Cryptoccous