Course Code: Course TitleMLS-046

Module #1 Student Activity Sheet

Lesson title: INTRODUCTION TO MYCOLOGY Materials:

Learning Targets: Module, Reference Book, Manual, Lap top

1. differentiate the morphological and cultural 1. Beneke, Everett (1999). Smith, Ph.D. Scope of
characteristics of fungi. Monograph on Human Mycoses, Kalamazoo,
2. categorize the diagnostic methods used for fungal Michigan; Upjohn Company
identification 2. Bulmer, glenn(1995). Fungus Disease in the
3. enumerate the harmful and beneficial effects of Orient,3rd ed. Manila: Rex Bookstore
fungi 3. McPherson and Pincus. (2018). HENRY’s Clinical
Diagnosis and Management by Laboratory Methods
23rd ed.,Singapore: Elsevier Pte.Ltd.

Internet Source:
Sridhar Rao PN (2006) Introduction to Mycology
https://www.microrao.com/micronotes/mycology.pdf

A. LESSON PREVIEW/REVIEW
The class will start with orientation which includes the following:
1. The core value and the VMG of the College and the school
2. Setting of policies and rules
3. Setting of expectations
4. Introduction to the course
5. Requirements of the course
Since we are utilizing RADLearning, a pre-recorded lecture is being uploaded in your FB page/google classroom.
Introduction
The term "mycology" is derived from Greek word "mykes" meaning mushroom. Therefore mycology is the study of
fungi. The ability of fungi to invade plant and animal tissue was observed in early 19th century but the first documented
animal infection by any fungus was made by Bassi, who in 1835 studied the muscardine disease of silkworm and proved
the that the infection was caused by a fungus Beauveria bassiana. In 1910 Raymond Sabouraud published his book Les
Teignes, which was a comprehensive study of dermatophytic fungi. He is also regarded as father of medical mycology.
Importance of fungi: Fungi inhabit almost every niche in the environment and humans are exposed to these organisms in
various fields of life.(Rao, S).

B.MAIN LESSON
Fungi
- Are multicellular members of the plant kingdom, and are referred to as thallophytes
- Usually filamentous – branched -somatic structure surrounded by the true cell wall.
Characteristics of a Fungi:
- 1. They are achlorophyllous ( can not manufacture its own food)
- 2. Ubiquitous ( present everywhere)
- 3. Exists in nature as saprophytes
- 4. Grow I the presence of acid and large amount of sugar (SDA- with pH of 5.6) which inhibits bacteria
- 5. Resistant to cold and are easily killed by high temperature

STRUCTURE AND GROWTH OF FUNGI

2 Basic Fundamental Structures: 2 Morphologic Forms of Fungi
1.Hyphae 1. Yeast
2. Spores 2. Mold

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 Course Code: Course TitleMLS-046
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Yeast:
- They produce moist, creamy, opaque or pasty colonies 0.5-3.0 mm in dm on culture media
- Single-celled/ unicellular structures with a thick cell wall
- Most reproduce by asexual budding, few by binary fission

Mold
- Produces multicellular filamentous colonies: Fluffy, cottony, wooly or powdery
Structure of Molds:
- 1. Hyphae : the basic structural unit of mold which can be divided in to:
⮚ Septate ( with septum)
⮚ Aseptate/ Coenocytic ( without septum)
⮚ Mycelium (when hyphae overlaps one from the other), hyphae forms a mass of intertwining
strands
Which can be divided into 2: a. Vegetative or Substrate b. Aerial or Reproductive mycelium

Morphologic Form of Fungi

COMMON FORMS OF HYPHAE DESCRIPTION ILLUSTRATION

1.Antler Hyphae/Favic Chandelier Curved, freely branching and antler in
appearance

2.Racquet hyphae Enlarged, club-shaped with the

smaller end attached to the large end
of the adjacent club-shaped strands
Spiral hyphae Coiled or corkscrew seen within
hyphal strands, Frequently found in
dermatophytes

Dimorphism
- The capability of an organism to grow in more than one form under different environment

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- Example. Sporothrix schenkii

Monomorphic
- An organism that grows only in one form ( mold/ Sparobic/ hyphal)may it be at room temperature or at a higher
temp
REPRODUCTIVE AND MULTIPLICATION OF FUNGI
- Multicellular fungi reproduce by conversion of a spore into a vegetative fungus
- Spores are functionally similar to a seeds of a higher plant

METHODS OF REPRODUCTION

1. Sexual (Teleomorph)= perfect fungus; is associated with the formation of specialized structures that facilitates
fertilization and nuclear fission resulting in the formation of specialized spores

⮚ A. Zygospores/Zygomycetes = derived from fusion of identical cells from the same hyphae
⮚ B. Ascospores/Ascomycetes = enclosed in a specific sac called ascus (asci)
⮚ C. Basidiospores/Basidiomycetes = enclosed in a club-shaped structures called basidia or basidium
⮚ D. Oospores = derived from fusion of non-identical cells from the same hyphae

ILLUSTRATIONS:

Zygospores Ascospores Basidiospores Oospores

2. Asexual (anamorph) = imperfect fungus (Fungus imperfecti) ; a new colone is formed without the involvement of a
gamete and without nuclear fusion; a type of sporulation seen in most fungi encountered I the clinical laboratory and
occurs strictly by mitosis

A. Thalospores = derived from the cells of the thallus or body of the fungi
TYPES OF THALOSPORES DESCRIPTION ILLUSTRATION

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A.1.Blastospores Buds formed by budding

Ex. Candida albicans process, sprouting from
Cryptococcus neoformans the surface of the parent
cell

A.2.Arthrospores/Arthroconidia Arise by fragmentation of

the ends of hyphae at
the point of septation;
square barrel-shaped
thick walled cells

A.2. Oidia When hyphal cells

Example:Geotrichum candidum separate from one
another to form flat
ended spores

A.3. Enlarged, round

Chlamydospores/Chlamydoconidi unicellular thick-walled
a structures that are
3 TYPES formed during
1. Terminal- found at the hyphal tip unfavorable conditions;
2. Intercallary- found within the formed by the
hyphal strands enlargement of a hyphal
3. Sessile- found at the side of the cell
hyphal strand
A.4. Sporangiospores Born internally within a
sac called
“SPORANGIUM”, which
develops at the tip of the
sporangiophore

⮚ Conidia = asexual spores produces singly or in groups (en-grape) by specialized vegetative strands/branch
called Conidiphore (borne externally not with in)

NOTE: Some conidiophore terminate into swollen structure called VESICLE; From the surface of the vesicle are formed
secondary flask-shaped or bottle called PHIALIDES or STERIGMA which in turn give rise to long chains of conidia as
seen in Aspergillus
In Penicillium, the structure known as Penicillus (brush-like structure) whereas each branch terminates in
secondary branches(metulae) and phialides from which chains of conidia are borne.

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2 Sized of Conidia
1. Microconidia/Microaleuriospores
- Small, unicellular conidia, maybe round, elliptical or pyriform (pear-shaped)
- Usually born directly on the side of the hyphal strands or at the end of a long or short conidiophore
2. Macroconidia/Macroaleriospores
- Large, multicellular conidia; multi-septate, clavate or spindle-shaped
- Usually borne on a short to long conidiophore
- Echinulate-rough and spiny; - Catenate-conidia in chain

DIAGNOSTIC METHODS USED FOR FUNGAL IDENTIFICATION

1. Direct Examination:
A. Wet Mount ( Temporary Mounts)
A.1. KOH (10-20%)
• Used to clear and dissolve debri making fungal elements prominent
• For direct examination of infected materials
• Specimen: skin, nails, skin scrapings, sputum, bone marrow, pus, exudates from draining sinus
tract
• Gentle heat increases the rate of clearing to enable one to see fungal elements better
• Observe for: hyphae, budding yeast cells or any mycelial filaments
• KOH is recommended in the following:

A.2. India Ink

● For identification of Cryptococcus neoformans .
● Ideal specimen:
CSF (meningeal form)
Sputum (pulmonary form)
● Look for encapsulated yeast cells
● Follows negative staining therefore capsule is readily demonstrated

A.3. Lactophenol Cotton Blue

● Stained used is AMAN Medium
● Preserves and stains fungi( shades of blue)
● Contains lactic acid, phenol and cotton blue which is excellent for mounting most fungi
● Specimen
Skin scrapings, hair and nails
Observe for spores, yeast cells and hyphae
B. Fluorescence
B.1. Calcoflour White Stain

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● Detects fluorescence under fluorescent microscope

B.2. Wood’s lamp
● Infected hair fluorescence bright yellow green under UV light
C. STAINING
STAINS DESCRIPTION
1. Gram Staining (Permanent Mounts) To see if fungus is a contaminant with bacterium
All fungi are gram (+)
2.PAS Best for visualizing fungi in skin scraping or tissue
If dematiaceous, appears as dark brown/black
3. Wright’s Stain or Giemsa Gridley, Gomori-Methenamine Silver
Excellent for staining yeast cells of H. capsulatum in
tissue
4. Papanicolau method Best stain for B. dermatitidis
5. Acridine Orange Ideal for T. versicolor
6. Acid Fast Stain (Kinyoun) Useful in the differentiation of Nocardia from Actinomyces
Hyphae of Nocardia steroids and Nocardia brasilliensis
are partially acid fast

Recommendation for Fungal Culture Media

- 1. Media with or without enrichment should be used (5-10%) sheep's RBC
- 2. Media with or without cyclohexmide (inhibits growth of fungi) should be used
- 3. All should contain antibacterial agents like chloramphenicol
NOTE:
• Culture should be incubated at RT for 30 days before reporting negative
• Culture should be examined at least 3 times a week during incubation
• Recommended to use agar plates or screw capped tubes for the recovery of fungi

Disadvantage of Culture Tubes:

• This will lead to poor isolation of colonies
• Reduce surface area of culture
• Tendency to promote anaerobiasis
• Cotton plugged tubes with culture media are not ideal or unsatisfactory for fungal cultures

Serologic Test:
• A significant rise in antibody titer to confirm the diagnosis
1. Complement fixation= for Cocciioidomycosis, Histoplasmosis, Blastomycosis
2. Latex Agglutination= for Cryptococcosis
3.Precipitation test

CHECK FOR UNDERSTANDING (25 minutes)

Answer the following questions:

1. It is considered to be the basic structural unit of fungi?

2. Enumerate the two (2) basic fundamental structure of fungi

3. A specialized vegetative strands /branch where vesicle is born

4. A term which refers to a hyphal that forms a mass of intertwining strands

5. What are the two (2) structures of molds

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6. Enumerate and illustrate the types of chlamydoconidia (for illustration, please refer to page 4; Types od
Chlamydoconidia)

7. Give an example of fungi which exhibits thermal dimorphism

8.Enumerate and illustrate the 3 types of Hyphae( for illustration and other examples please refer to page 3)
(For Types and forms of Vegetative Hyphae)

9. What do you call a hyphal cells which separates from one another to form a flat ended spores

10. Differentiate Sexual from Asexual reproduction of fungi>

C. LESSON WRAP - UP

-Some 200 "human pathogens" have been recognized from among an estimated 1.5 million species of fungi.
-Fungi exist in two fundamental forms; the filamentous (hyphal) and single celled budding forms (yeast). But, for the
classification sake they are studied as moulds, yeasts, yeast like and dimorphic fungi. All fungi have typical eukaryotic
morphology.
-They have rigid cell wall composed of chitin, which may be layered with mannans, glucans and other polysaccharides in
association with polypeptides.
-Some lower fungi possess cellulose in their cell wall. Some fungi such as Cryptococcus and yeast form of Histoplasma
capsulatum possess polysaccharide capsules that help them to evade phagocytosis.
-Inner to the cell wall is the plasma membrane that is a typical bi-layered membrane in addition to the presence of sterols.
-Fungal membranes possess ergosterol in contrast to cholesterol found in mammalian cells.
- The cytoplasm consists of various organelles such as mitochondria, golgi apparatus, ribosomes, endoplasmic reticulum,
lysosomes, microtubules and a membrane enclosed nucleus.
-A unique property of nuclear membrane is that it persists throughout the metaphase of mitosis unlike in plant and animal
cells where it dissolves and re-forms. The nucleus possesses paired chromosomes.

Beneficial Effects of Fungi:

1. Decomposition - nutrient and carbon recycling.
2. Biosynthetic factories. The fermentation property is used for the industrial production of alcohols, fats, citric, oxalic and
gluconic acids.
3. Important sources of antibiotics, such as Penicillin.
4. Model organisms for biochemical and genetic studies. Eg: Neurospora crassa
5. Saccharomyces cerviciae is extensively used in recombinant DNA technology, which includes the Hepatitis B Vaccine.
6. Some fungi are edible (mushrooms).
7. Yeasts provide nutritional supplements such as vitamins and cofactors.
8. Penicillium is used to flavour Roquefort and Camembert cheeses.

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9. Ergot produced by Claviceps purpurea contains medically important alkaloids that help in inducing uterine contractions,
controlling bleeding and treating migraine.
10. Fungi (Leptolegnia caudate and Aphanomyces laevis) are used to trap mosquito larvae in paddy fields and thus help
in malaria control.

Harmful Effects of Fungi:

1. Destruction of food, lumber, paper, and cloth.
2. Animal and human diseases, including allergies.
3. Toxins produced by poisonous mushrooms and within food (Mycetism and Mycotoxicosis).
4. Plant diseases.
5. Spoilage of agriculture produce such as vegetables and cereals in the godown. 6. Damage the products such as
magnetic tapes and disks, glass lenses, marble statues, bones and wax.

READING ASSIGNMENT:

1. Lists Culture Media according to:

a. Media for primary isolation
b. Special purpose media
2. Enumerate and give the corresponding fungi, and its purpose
3. How to properly maintain stock culture

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