Kingdom Fungi
Dr. ROD ALFONSO
Head, Development and Quality Assurance Unit
Requirements to get Good
Grade
1. Perfect Attendance
2. Participate actively in classroom activities
3. Pass assignment on time
4. Pass all quizzes and major exams
5. Good attitude
Learning Objectives
At the end of the lesson, students will be able to:
1. Define mycology; Define a fungus
2. Describe the characteristics of fungi
3. Describe the distribution of fungi in nature
4. Explain why there are few invasive fungal infection.
5.
6.
Describe the characteristics of yeasts and how they reproduce
Discuss the significance of yeast in food industry, in
medicine and biofuel industry.
7. Describe molds
8. Differentiate hypha, thallus and mycelium
9. Differentiate between septate and coenocytic hyphae
10. Explain dimorphic fungi
11. Discuss the beneficial and harmful effects of fungi
Mycology
Mycology is the study of fungi ( yeasts, molds
and mushrooms)
001
What is a fungus?
• A eukaryotic, heterotrophic organism devoid
•
•
of chlorophyll that obtains its nutrients by
absorption, and reproduces by spores.
The primary carbohydrate storage product of
fungi is glycogen.
Most fungi have a thallus composed of
hyphae (sing. hypha) that elongate by tip
growth
The Characteristics of Fungi
* Eukaryotic(true
nucleus)
* Larger, more complex
than bacteria
* Lack chlorophyll
* Chitin, glucan &
mannan are the
complex carbohydrates
found in their cell wall
* Reproduce sexually
and asexually
* Cell wall contains
ergosterol
* Heterotrophic (require
organic carbon)
Fungal Fast Facts
• Fungi are all
•
•
around us
We touch them, we
swallow them, we
breathe them
There are more
than 1.5 million
fungal species in
nature
• Yet only about 100
•
•
cause human disease
Most cause superficial
infections, some cause
allergic reactions
Few cause invasive
infections
Why so few Invasive Infections?
Host/Pathogen Balance:
Normal Circumstances
Anatomical
barriers
Host
Factors
Protection
Adaptive
immunity
Virulence
Fungal
Factors
Fungal
Burden
Innate
defenses
Infection
Yeast - Major
Characteristics
•
•
•
Unicellular Fungi,
nonfilamentous, oval or
spherical cells
Eukaryotic
Facultative anaerobes
* When oxygen is available, they
carry out aerobic respiration.
* When oxygen is not available, they
ferment carbohydrates to produce
ethanol and carbon dioxide.
•
Capable of forming colonies on
solid culture media (see pictures on
the right).
Yeast - Reproduction
They reproduce either asexually (most common) or sexually.
•Asexual reproduction is through budding or binary fission.
•Sexual reproduction (if any) results in the formation of the
appropriate spore structure.
Fission
Budding
Saccharomyces cerevisiae
Spores
Schizosaccharomyces octosporus
Yeast Significance
 Food Industry
• Fermentation of bread, beer, and wine. E.g. Saccharomyces
cerevisiae (also called baker’s yeast or sugar yeast) used in baking
and fermenting of alcoholic beverages.
 Medical
• E.g. Candida albicans - common in the human mouth, but can
become pathogenic and cause Candidiasis (oral and/or genital
infection).
 Biofuel Industry
•Production of ethanol for car fuel.
2. Molds and Fleshy Fungi
Multicellular, filamentous fungi.
Identified by physical appearance, colony characteristics, and
reproductive spores.
* Thallus: Body of a mold or fleshy fungus. Consists of many
hyphae.
* Hyphae (Sing: Hypha): Long filaments of cells joined
together.
Septate hyphae: Cells are divided by cross-walls (septa).
Coenocytic (Aseptate) hyphae: Long, continuous cells that are not
divided by septa.
Hyphae grow by elongating at the tips.
Each part of a hypha is capable of growth.
Vegetative Hypha: Portion that obtains nutrients.
Reproductive or Aerial Hypha: Portion connected with
reproduction.
* Mycelium: Large, visible, filamentous mass made up of many hyphae.
Characteristics of Fungal Hyphae:
Septate versus Coenocytic
Hyphae
• Tubular
• Hard wall of chitin
• Crosswalls may
•
•
form compartments
(± cells)
Multinucleate
Grow at tips
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
Mycelium: Large, Visible Mass of
Hyphae
Dimorphic Fungi

Can exist as both multicellular fungi (molds) and yeasts.

Many pathogenic species.


Mold form produces aerial and vegetative hyphae.

Yeast form reproduces by budding.
Dimorphism in pathogenic fungi typically depends on
temperature:

At 37oC: Yeast form.

At 25oC: Mold form.
Yeast at 370C

Mold at 250C
Dimorphism in nonpathogenic fungi may depend on other
factors: Carbon dioxide concentration.
HUMAN-FUNGUS INTERACTIONS
•
•
Beneficial Effects of Fungi
* Decomposition - nutrient and carbon recycling.
* Biosynthetic factories. Can be used to produce drugs, antibiotics,
alcohol, acids, food (e.g., fermented products, mushrooms).
* Model organisms for biochemical and genetic studies.
Harmful Effects of Fungi
* Destruction of food, lumber, paper, and cloth.
* Animal and human diseases, including allergies.
* Toxins produced by poisonous mushrooms and within food (e.g.,
grain, cheese, etc.).
* Plant diseases.