1. Fungi
L. Dalia Kamal Eldien
MSc in Microbiology
Lecture NO: 8

2. Outlines At the end of this lecture, the student should know:-
Definition of mycology
Benefit of fungi
Harmful effects of fungi
General properties of fungi
Morphology of fungi

3. Introduction
The mycology is a discipline of biology which deals with the study of fungi.
The medical mycology is a branches that deal with the study of pathogenic fungi to man and animal, the fungal infections now a day are in increasing rate
Fungi can cause mild infections or trigger allergic reactions or produce serious life-threatening disease.

4. Beneficial effects of fungi
1-Decomposition :
Lower fungi produce enzyme break down the organic dead materials
2-Biosynthetic factories:
The fermentation property is used for the industrial production of alcohols, fats, citric& gluconic acids
3-Important sources of antibiotics:
Such as Penicillin (produced by Penicillium chrysogenum), Cephalosporin produced by (Cephalosporium acremonium)

5. Beneficial effects of fungi
5-Model organisms for biochemical and genetic studies e.g.: Neurospora crassa, Saccharomyces cerviciae is extensively used in recombinant DNA technology
6-Some fungi are eatable e.g. Mushrooms
7-Some fungi are used in food production: e.g. Yeasts used in bakery, yogurt, cake……..

6. Mushrooms

7. Cake& cheese (yeast)

8. Harmful effects of fungi
Destruction of food, lumber (wood), paper, and cloth.
Food poisoning, toxins produced by poisonous mushrooms (Mycetism and Mycotoxicosis).
Plant diseases.
Damage of agricultural products (vegetables& cereals in the godown)
Damage the products such as magnetic disks, glass lenses, marble statues, bones and wax.
Animal and human diseases.

9. Destruction of food by fungi

10. General properties of fungi
They are eukaryotic cells contain membrane bound cell organelles including nuclei, nucleic acid (DNA&RNA) mitochondria, Golgi apparatus, endoplasmic reticulum, lysosomes etc…….
Possesses 80S ribosome's.
Have Ergosterols in their membranes
Have a rigid cell wall made of chitin
Non-motile (this feature that separates them from animals)

11. Eukaryotic cell

12. General properties of fungi
Are heterotrophs, but fungi lack chlorophyll
Food storage is generally in the form of lipids and glycogen.
All fungi require water and oxygen and there is no obligate anaerobes.
Typically reproduce asexually and/or sexually .

13. Reproduction in fungi Fungi can reproduce asexually or/ and sexually
Asexual reproduction is the commonest mode in most fungi
Asexual spores are produced following mitosis, where as sexual spores are produced following meiosis.
A fungus that reproduces sexually is known as a teleomorph.
A fungus that reproduces asexually is known as a anamorph

14. Morphology of fungi Dimorphic fungi Polymorphic fungi
Fungi exist in two fundamental forms;
The filamentous or molds form
The yeast form
Dimorphic fungi
Polymorphic fungi

15. Filamentous fungi
The main structure element are cylindrical tube like structures refer to as hypha(e)
The hyphae may be branched or non branched
They may be septate or aseptate (coenocytic), hyphae usually have cross walls that divide them into numerous cells called septa& have small pores through which cytoplasm is continuous throughout the hyphae.

16. Filamentous fungi Amass of hyphae is known as mycelium
Most molds have a fuzzy or woolly appearance because of the formation of mycelia

17. Septated& non septated hypha

18. Identify?

19. Yeast
Yeasts are unicellular cells with different shape and size round, oval or elongated
Some yeast are produce polysaccharide capsule
They reproduce by budding or binary fission.
During fission, two cells of equal size are formed.
These cells continue to grow from the tips of the cell and divide only after a medial fission is formed.

20. Budding in yeast
This process involves lysis of the yeast cell wall so that a bud (blastospore)can form.
As this structure enlarges, the nucleus of the parent cell undergoes mitosis.
Once the new nucleus is passed into the daughter cell, a septum forms and the daughter cell breaks free.

22. Budding in yeast
In some cases the buds fail to detach from mother cell, and elongate thus forming a chain of elongated hyphae like filament called pseudohyphae,
This property is seen in Candia albicans.

23. Budding in yeast

24. Dimorphic fungi
The term dimorphism refers to the ability of some fungi to exist in two forms, dependent on growth conditions.
Dimorphic fungi have the ability to shift from the yeast form to the filamentous (mold) form, and vice versa.
 They can exist in filamentous or yeast form depending on the condition of growth, mainly the temperature

25. Dimorphic fungi
The yeast or tissue state is seen in vivo or when the organism is grown at 37° C with increased CO2.
The mold phase is seen when the organism is grown at room temperature (22° to 25° C) in ambient air conditions
Example: Histoplasma Capsulatum

26. Polymorphic fungi
Polymorphic fungi have both yeast and filamentous forms in the same culture.
This characteristic occurs despite growth conditions and is best observed in Exophiala species, in which the yeast phase is typically observed initially, followed by the filamentous phase as the colony ages.

28. Introduction
Fungi Kingdom show a great diversity in morphology and habitat.
This Kingdom is enormous, the identified species and those not yet classified add up to over 300,000 species.
The majority of these species are microscopic fungi
A relatively small number of species have reproductive systems known as “mushrooms” that can be easily observed.

29. Reproduction in fungi Fungi reproduce asexually and/or sexually
Asexual reproduction is the commonest mode in most fungi
Asexual spores are produced following mitosis where as sexual spores are produced following meiosis.

30. Classification of fungi
There are many ways for fungi classification, but the most practical approaches based on:
Method of reproduction (Sexual or asexual)
Type of hyphae (septated or non septated)

31. Classification of fungi
Basing on those criteria they classify the fungi in to four phyla
Zygomycota, (now a day known as Glomeromycota)
Ascomycota
Basidiomycota
Deuteromycota (in past known as fungi imperfecti)

32. Scientific classification
Kingdom: Fungi
Phylum: Zygomycota (Glomeromycota)
Order: Zygomycetes

33. Zygomycetes Hyphae are aseptate Reproduce sexual and asexual
Commonly known as bread molds

34. Scientific classification
Kingdom: Fungi
Phylum: Ascomycota
Class : Ascomycetes

35. Ascomycetes The hyphae of ascomycetes are septate
Reproduce sexual and asexual

36. Scientific classification
Kingdom: Fungi
Phylum: Basidiomycota
Class: Basidomycetes

37. Basidomycetes Have septated hyphae Reproduce sexually only
Less medically important group
Example: Mushrooms

38. Deuteromycetes Have septated hyphae
Reproduce sexually and asexually, but mostly asexually
Are the most medically important group

39. Home work
Compare between bacteria, virus& fungi

40. Sources
Lippincott's Illustrated Reviews: Microbiology, 3rd Edition (2012)- Richard A. Harvey- Bruce D. Fisher- Richard A. Harvey- (chapter 20)
Textbook of Diagnostic Microbiology-Fifth edition- Connie R. Mahon, MS- Donald C. Lehman, EdD, MT(ASCP), SM(NRM) - George Manuselis, MA, MT(ASCP)- Elsevier (2015) (Part II –page 589)