2. Introduction
The term Mycology derived from the Greek word
Mykos = mycete = fungus
a direct counterpart of Latin word meaning
mushroom (fungus ).
Mycology is the study of fungal biology, fungal
ecology, fungal diversity, Genetic of Fungi,
fungal evolution and the important impacts they
have on humans .
5. Some mycology terms
mycology
study of fungi
mycologists
scientists who study fungi
mycotoxicology
study of fungal toxins and their effects
Mycoses
diseases caused by fungi
◦ Mycetism
Clinical entity produced by ingestion of
toxin along with fungus
6. Definition of Fungi (Fungus)
Fungus Derived from Latin word
“FUNGOUR” meaning “To Flourish.
One of the most important organism on this
planet .
Eukaryote, spore reproducing, achlorophyllous .
with absorptive nutrition that reproduce both
sexually , asexually and parasexually ,usually
have filamentous body, branched, the somatic
structure known as hyphae (pl, hypha).
Collective mass of Hyphae form a network
called a mycelium (pl. mycelia).
7.
8. Features Viruses Bacteria Fungi
Size 0.02-0.3 µ 0.3-2µ 3-10µ and more
Cell Type Acellular Prokaryote Eukaryote
DNA/ RNA Either Both Both
Nucleic acid
replication
Host cell Continuous G & S phase
Replication Complex Binary fission Mitosis/ Meiosis
Organelle Uses host Not membrane bound Membrane bound
Ribosomes None 70S(30S+50S) 80S(40S+60S)
Cell memb Env/Non env No sterol Ergosterol
Cell wall None Peptidoglycan Chitin, Glucan
9.
10. Fungi are better able to withstand certain
extreme environmental conditions than most
other microorganisms. .
For example, yeasts and moulds can grow in
substrates containing concentrations of sugars
that inhibit most bacteria, e.g. jams and jellies
are spoiled by moulds but not bacteria.
moulds can generally tolerate more
acidic conditions than most other microbes.
11. Moulds have diverse Temperatures
growth
Fungi grow over a wide range of
temperatures, ranging from 22 to 30 oC
Mesophiles
pathogenic species have higher
temperature optimum, generally 30-37 oC.
Thermophiles
Some fungi grow at 40-100 oC and thus
can cause spoilage of foods (meat,
vegetables etc.)
Psycrophiles: in cold storage.0 or -10
12.
13. 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.
H. Complex cytoplasm with internal organelles, microfilaments
14. 1. fungi are heterotrophic ( “other feeding,” must feed on
preformed organic material), not autotrophic ( “self feeding,”
make their own food by photosynthesis).
- Unlike animals (also heterotrophic), which ingest then digest,
fungi digest then ingest. to accomplish this
-Fungi produce exoenzymes : powerful hydrolytic enzymes
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.
M. Most fungi have very small nuclei, with little repetitive DNA.
N. Mitosis is generally accomplished without dissolution of the
nuclear envelope
O. Lack flagella
18. Aeration
The fungi include species that are
obligately aerobic (eg. most
Zygomycota),
obligately anaerobic (eg. Many
fungi)
19. Fungi growth requirements
1. water
2. A favorable temperature
3. an abundance oxygen
4. a digestible food or potential energy
source
5. light
6. pH range
7. vitamins and minor elements
20. Hyphae
Hyphae are designed to increase the surface area of
fungi and thus facilitate absorption
May grow fast, up to 1 km per day, as they spread
throughout a food source
May be coenocytic, having no septa between cells, or
septa may be present with pores through which
cytoplasm can flow moving nutrients through out the
fungus
Parasitic fungi have modified hyphae called
haustoria, which penetrate the host tissue but
21. 1. Septate hyphae: In most fungi, hyphae are divided
into cells by internal cross-walls for example
“Aspergillus”.
2. Coenocytic hyphae (non-septate hyphae):
meaning their hyphae are not partitioned by septa.
3. Pseudo hyphae: They are the result of incomplete
budding where the cells remain attached after
division, and Yeast can form pseudohyphae.
Types of Hyphae in Fungi
28. Hyphal growth
Hyphae grow from their tips
Mycelium = extensive, feeding web of
hyphae
Mycelia are the ecologically active
bodies of fungi
This wall is rigid Only the tip wall is plastic and stretches
29. MYCELIUM
Intertwined filamentous mass formed by
hyphae, visible to eye
Forms when environmental conditions are right
Vegetative mycelium: Mycelial portion
remaining INSIDE the substrate to obtain
nutrition
Reproductive mycelium: Mycelial portion
extends into air ,responsible for SPORE
reproduction
31. Types of mycelium
1. Submerged mycelium are those that penetrates the
surface of the medium and absorbs nutrients.
2. Aerial mycelium are those that grow above the agar
surface
3. Fertile mycelium are aerial hyphae that bear
reproductive structures such as conidia or sporangia.
32.
33.
34.
35. Cell wall components
Consists of chitin not peptidoglycan like
bacteria.
Thus fungi are insensitive to antibiotics as
penicillins.
Also the fungal cell wall contain other
polysaccharide, B-glucan, which is the site
of action of some antifungal drugs.
36. In addition to chitin, glucan, and mannan,
cell walls may contain lipid, protein,
chitosan, acid phosphatase, amylase,
protease, melanin, and inorganic ions
(phosphorus, calcium, and magnesium)
The outer cell wall of dermatophytes
contains glycopeptides that may evoke both
immediate and delayed cutaneous
hypersensitivity
37.
38.
39. Mode of nutrition
Fungi get carbon from organic sources
Hyphal tips release enzymes
Enzymatic breakdown of substrate
Products diffuse back into hyphae
Product diffuses back
Nucleus hangs back
and “directs”
Heterotrophic – 'other food‘
40. • Heterotropic by absorption
– secrete digestive enzymes
– digest macromolecules outside the body
– absorb digested nutrients
• Three nutritional modes
– Saprophytic = digestion of dead organisms
– Parasitic = digestion of live organisms,
causing disease
– Mutualistic = beneficial relationship for two
independent organisms
41. • Obligate Saprobes:
Saprobe fungi incapable of infecting
living organisms to cause diseases.
eg: Rhizopus sp.
• Facultative Saprobes:
Fungi capable of causing disease.
eg: Pythium sp.
