Fungal spore 1

Mycology

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Department of Laboratory Medicine
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MYCOLOGY
Lecture No. 02(Fungal Spore)"
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Sk. MIZANUR RAHMAN
Lecturer, Mycology
MS in Biotechnology & Genetic Engineering (UODA)
MS in Microbiology (SUB)

2. Reproduction
•Filamentous fungi
–Asexually by fragmentation of hyphae
–Asexual and sexual reproduction by spores
•Yeasts
–Asexually by budding or fission:
 Fission: e.g. Schizosacchromyces pombe.
 Budding e.g. Saccharomyces cerevisiae.
–Sexual reproduction by spores (in high stress
condition)

3. Terms
Fragmentation can occur whereby mycelium are torn
apart by external forces and these bits can start new
individuals if conditions are favourable.
Fission is a simple splitting of a cell into two new daughter
cells by constriction and the formation of a cell wall e.g.
yeast.
Budding is the production of small outgrowths (bud) from
a parent cell and as the bus is formed, the nucleus of the
parent cell divides and one daughter nucleus migrates
into the bud. The bud increase in size while still attached
to the parent cell and eventually breaks off and forms a
new individual. Yeast reproduce via budding but do some
other fungi in different conditions.

4. Asexual Spores
•More important type of reproduction as it
occurs several times throughout the season.
•Produced by fragmentation of aerial
hyphae
•Progeny genetically identical to parent

5. Spores can be of various colours, depending on:
the colour of hyaline (green, yellow, orange, red,
brown, black);
 shape (oval, oblong, needle-shaped, helical);
number of cells (one to many);
arrangement of cells and where they are
situated.
Several types of spores:
 Conidiospores
Blastospores
Chlamydospores
Sporangiospores
Arthrospores

6. Chlamydospores
Arthrospores
Sporangiospores
Conidiospores
Blastospores
1
3
1A
1B
2

7. ASEXUAL SPORES
Conidiospore
–Multiple (chains) or single spores formed at
the end of an aerial hypha
–Not enclosed within a sac
–Eg: Aspergillus spp. and Penicillium spp.

8. Conidial fungus
•reproduces by means of asexual
spores called conidia
•Conidia vary greatly in shape, size
and color
•Most of the common household
molds & mildews are conidial fungi

9. ASEXUAL SPORES (cont.)
•Blastospores
–A bud coming off the parent cell
– Candida albicans
Blastospore

11. ASEXUAL SPORES (cont.)
•Chlamydospore
–Formed within hypha
–Thick-walled spore
•Candida albicans

12. Chlamydospores
•The chlamydospore is a method of producing a
substantial resting spore very quickly
•Nutrient is shunted from adjacent cells into a
preferred cell and it swells up, converts nutrient
materials to oil droplets for efficient storage, then
rounds off with a thick, often roughened outer wall
for protection

13. •Sporangiospores
–Hundreds formed within a sac
(sporangium) at the end of an aerial
hypha
–Rhizopus spp.
ASEXUAL SPORES (cont.)

15. Sexual Reproduction
•Union of two nuclei.
•The entire thallus can be converted into
one or more reproductive structures.
•Somatic and reproductive phases do not
occur together in the same individual and
this is called holocarpic.
•In majority of fungi, only a portion of the
thallus give rise to reproductive organs and
they are called eucarpic.

16. Sexual Spores
•Three phases of development
–Plasmogamy: a union of two protoplasts bringing
about the nuclei close together and within same cell.
- haploid nucleus of a donor cell (+) penetrates the
cytoplasm of a recipient cell (-)
–Karyogamy: Fusion of the two nuclei. Formation of a
dikaryon – a binucleate cell containing two nuclei from
each parent
- the 2 nuclei fuse to form a diploid nucleus
–Meiosis: diploid nucleus gives rise to haploid nuclei
- Sexual spores, some + , some -,some recombinants
- Sexual spores used to classify fungi into divisions

17. Sexual Reproduction
•Ascospores
•Basidiospores
•Zygospores

18. Molds with septate hyphae and some yeasts.
Sexual Reproduction: Ascospores enclosed in a sac-like
structure (ascus).
Include common antibiotic producing fungi and yeasts, and
several human pathogens.
–Penicillium notatum (Produces penicillin)
–Saccharomyces (Brewer’s yeast)
–Trychophyton (Athlete’s foot)
–Aspergillus (Carcinogenic aflatoxin in peanuts),
Ascomycota (Sac Fungi)

19. Have septate hyphae.
Include mushrooms, toadstools, rusts, and smuts.
Sexual Reproduction: Produce basidiospores: Spores
formed externally on a club shaped sexual structure or
base called basidium.
 Examples:
– Amanita: Mushroom produces lethal toxins to humans.
–Claviceps purpurea: Produces ergot toxin in wheat
and rye.
Basidiomycota (Club Fungi)

20. Also known as bread molds.
Sexual Reproduction: Occurs through conjugation, the joining
of hypha of two different strains (plus and minus).
Zygospores: Sexual spores which are enclosed in a thick,
resistant wall.
Generally not pathogens.
Rhizopus stolonifer: Common black bread mold. May cause
opportunistic infections in diabetes patients
Zygomycota (Conjugation Fungi)

21. Life Cycle of a Zygomycete: Black Bread Mold (Rhizopus)
Reproduces Asexually and Sexually

22. A. Aspergillus; B. Penicillium; C. Geotrichum; D. Trichophyton;
E. Microsporum; F. Epidermophyton and G. Rhizopus.  From
Medical Microbiology, 1990, Murray, et al., p. 300, Fig. 28-2.