Introduction to     Mycology03/04/12   Masdiana Padaga   1
Fungi versus fungi “fungus” is used inclusively for a heterogenous group of organisms that have traditionally been studied...
Introduction to Mycology Mycology is the study of fungi –  Yeast  Mold 03/04/12      Masdiana Padaga      3
MycologyYeasts and molds have different structural andreproductive characteristics     Yeast are unicellular, nucleated ro...
MycologyFungi serve both beneficial and harmfulroles in our environment     Molds used in the production of cheeses and   ...
CHARACTERISTICS OF FUNGI1. Yeastsx Unicellular fungi, nonfilamentous, typically oval or  spherical cells. Reproduce by mit...
CHARACTERISTICS OF FUNGI (Continued)2. Molds and Fleshy Fungix Multicellular, filamentous fungi.x Identified by physical a...
CHARACTERISTICS OF FUNGI (Continued)Dimorphic Fungix Can exist as both multicellular fungi (molds) and yeasts.x Many patho...
03/04/12   Masdiana Padaga   9
Hyphae (singular, hypha) Cylindrical, branching filaments composed of a tubular cell wall filled with cytoplasm and organe...
Septa Septa—regular cross-walls formed in hyphae. Hyphae with septa are septate, those lacking septa except to delimit rep...
Characteristics of Fungal Hyphae:Septate versus Coenocytic   03/04/12     Masdiana Padaga     12
Mycelium: Large, Visible Mass of Hyphae   03/04/12     Masdiana Padaga   13
Fungal cell Structure 03/04/12   Masdiana Padaga   14
Fungal cell wall composition Structural components:      chitin microfibrils [ß(1-4)-linked polymer of      N-acetylglucos...
Other cell wall components Antigenic glycoproteins, agglutinans, adhesions—on cell wall surface Melanins—dark brown to bla...
03/04/12   Masdiana Padaga   17
Fungal nuclei      1--3 µm diam      3--40 chromosomes      Up to 13--40 Mb (million base pairs) DNA      coding for 6,000...
Fungal nuclei Usually haploid Nuclear membrane persists during division Nuclear associated organelles (NAOs):      Associa...
Other organelles Mitochondria—flattened or plate-like mitochondrial cristae in Fungi (similar to animals) Golgi bodies—con...
Storage Compounds Glycogen, lipids and trehalose in fungi and animals Starch in plants 03/04/12        Masdiana Padaga    ...
LIFE CYCLE OF FUNGI Filamentous fungi can reproduce asexually by fragmentation of their hyphae. Fungal spores are formed f...
Arthrospores are formed by the fragmentationof septate hyphae  03/04/12        Masdiana Padaga       23
Chlamydospores are thick walled spores formed within a hyphae  03/04/12        Masdiana Padaga        24
Sporangiospores are formed within a sac  (sporangium) at the end of an aerial hyphae called  a sporangiophore   03/04/12  ...
Sporangiospores 03/04/12   Masdiana Padaga   26
Conidiospores are produced in a chain at the end of a  conidiophore. Unicellular conidiospores are called  microconidia   ...
Blastospores consist of a bud coming off the  parental cell  03/04/12         Masdiana Padaga       28
NUTRITIONAL ADAPTATIONS OF FUNGIFungi absorb their food, rather than ingesting it.x Fungi grow better at a pH of 5, which ...
Fungi are classified based on thetype of sexual spore that theyform 03/04/12    Masdiana Padaga   30
Zygomycota Have non-septate                         Zygospores  hyphea Have asexual  sporangiospores Form sexual  zygos...
Ascomycota    Have septate                        Ascospores inside an     hyphae                                        ...
 Basidiomycota  Have septate hyphae, asexual conidiospores  Have sexual basidiospores. Basidiospores are formed  external...
How do we identify molds in the lab?   Based on type of hyphae (septate versus non-septate)   Based on color of mycelium...
ECONOMIC IMPORTANCE OF FUNGI  25-50% of harvested fruits and vegetables are damaged by  fungi.  Fungal infections of plant...
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Mycology introduction week 5

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Mycology introduction week 5

  1. 1. Introduction to Mycology03/04/12 Masdiana Padaga 1
  2. 2. Fungi versus fungi “fungus” is used inclusively for a heterogenous group of organisms that have traditionally been studied by mycologists “Fungi” refers to the organisms in the Kingdom Fungi, the true fungi, also called the “Eumycota” 03/04/12 Masdiana Padaga 2
  3. 3. Introduction to Mycology Mycology is the study of fungi – Yeast Mold 03/04/12 Masdiana Padaga 3
  4. 4. MycologyYeasts and molds have different structural andreproductive characteristics Yeast are unicellular, nucleated rounded fungi while molds are multicellular, filamentous fungi Yeast reproduce by a process called budding while molds produce spores to reproduce Some yeast are opportunistic pathogens in that they cause disease in immuno-compromised individuals Yeast are used in the preparation in the variety of foods03/04/12 Masdiana Padaga 4
  5. 5. MycologyFungi serve both beneficial and harmfulroles in our environment Molds used in the production of cheeses and also serve an antimicrobial purpose (penicillin). Molds can be opportunistic infections in debilitated and immunosuppressed individuals.03/04/12 Masdiana Padaga 5
  6. 6. CHARACTERISTICS OF FUNGI1. Yeastsx Unicellular fungi, nonfilamentous, typically oval or spherical cells. Reproduce by mitosis: Fission yeasts: Divide evenly to produce two new cells (Schizosaccharomyces). Budding yeasts: Divide unevenly by budding (Saccharomyces). Budding yeasts can form pseudohypha, a short chain of undetached cells. Candida albicans invade tissues through pseudohyphae.x Yeasts are facultative anaerobes, which allows them to grow in a variety of environments. When oxygen is available, they carry out aerobic respiration. When oxygen is not available, they ferment carbohydrates to produce ethanol and carbon dioxide. 03/04/12 Masdiana Padaga 6
  7. 7. CHARACTERISTICS OF FUNGI (Continued)2. Molds and Fleshy Fungix Multicellular, filamentous fungi.x 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. x Septate hyphae: Cells are divided by cross-walls (septa). x 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. x Vegetative Hypha: Portion that obtains nutrients. x Reproductive or Aerial Hypha: Portion connected with reproduction. Mycelium: Large, visible, filamentous mass made up of many hyphae. 03/04/12 Masdiana Padaga 7
  8. 8. CHARACTERISTICS OF FUNGI (Continued)Dimorphic Fungix Can exist as both multicellular fungi (molds) and yeasts.x Many pathogenic species. Mold form produces aerial and vegetative hyphae. Yeast form reproduces by budding.x Dimorphism in pathogenic fungi typically depends on temperature: At 37oC: Yeast form. At 25oC: Mold form.x Dimorphism in nonpathogenic fungi may depend on other factors: Carbon dioxide concentration. 03/04/12 Masdiana Padaga 8
  9. 9. 03/04/12 Masdiana Padaga 9
  10. 10. Hyphae (singular, hypha) Cylindrical, branching filaments composed of a tubular cell wall filled with cytoplasm and organelles Most fungal hyphae are 2-10 µm diameter 03/04/12 Masdiana Padaga 10
  11. 11. Septa Septa—regular cross-walls formed in hyphae. Hyphae with septa are septate, those lacking septa except to delimit reproductive structures and aging hyphae are called aseptate or coenocytic. primary septa are formed as a process of hyphal extension and generally have a septal pore, which allows for cytoplasmic and organelle movement. Secondary or adventitious septa are imperforate, formed to wall off ageing parts of the mycelium. 03/04/12 Masdiana Padaga 11
  12. 12. Characteristics of Fungal Hyphae:Septate versus Coenocytic 03/04/12 Masdiana Padaga 12
  13. 13. Mycelium: Large, Visible Mass of Hyphae 03/04/12 Masdiana Padaga 13
  14. 14. Fungal cell Structure 03/04/12 Masdiana Padaga 14
  15. 15. Fungal cell wall composition Structural components: chitin microfibrils [ß(1-4)-linked polymer of N-acetylglucosamine] chitosan in Zygomycota [ß(1-4)-linked polymer of glucosamine] ß-linked glucans Gel-like components: Mannoproteins (form matrix throughout wall) 03/04/12 Masdiana Padaga 15
  16. 16. Other cell wall components Antigenic glycoproteins, agglutinans, adhesions—on cell wall surface Melanins—dark brown to black pigments (confer resistance to enzyme lysis, confer mechanical strength and protect cells from UV light, solar radiation and desiccation) Plasma membrane—semi-permeable 03/04/12 Masdiana Padaga 16
  17. 17. 03/04/12 Masdiana Padaga 17
  18. 18. Fungal nuclei 1--3 µm diam 3--40 chromosomes Up to 13--40 Mb (million base pairs) DNA coding for 6,000 to 13,000 genes Intranuclear division--nuclear envelope remains intact during mitosis (unlike plants and animals) 03/04/12 Masdiana Padaga 18
  19. 19. Fungal nuclei Usually haploid Nuclear membrane persists during division Nuclear associated organelles (NAOs): Associated with the nuclear envelope; function as microtubule-organizing centers during mitosis and meiosis • Spindle pole bodies  In fungi that lack a flagellated stage in lifecycle • Centrioles  In fungi and other organisms possessing flagellated stage in lifecycle 03/04/12 Masdiana Padaga 19
  20. 20. Other organelles Mitochondria—flattened or plate-like mitochondrial cristae in Fungi (similar to animals) Golgi bodies—consist of a single, tubular cisternal element (stacked, plate-like cisternae in animals and plants) Other types: ribosomes, endoplasmic reticulum, vacuoles, lipid bodies, glycogen storage particles, microbodies, microtubules, vesicles 03/04/12 Masdiana Padaga 20
  21. 21. Storage Compounds Glycogen, lipids and trehalose in fungi and animals Starch in plants 03/04/12 Masdiana Padaga 21
  22. 22. LIFE CYCLE OF FUNGI Filamentous fungi can reproduce asexually by fragmentation of their hyphae. Fungal spores are formed from aerial hyphae and are used for both sexual and asexual reproduction. 1. Asexual spores: Formed by the aerial hyphae of one organism. New organisms are identical to parent. x Conidiospore: Unicellular or multicellular spore that is not enclosed in a sac. x Chlamydospore: Thick-walled spore formed within a hyphal segment. x Sporangiospore: Asexual spore formed within a sac (sporangium). 2. Sexual spores: Formed by the fusion of nuclei from two opposite mating strains of the same species. New organisms are different from both parents. Masdiana Padaga 03/04/12 22
  23. 23. Arthrospores are formed by the fragmentationof septate hyphae 03/04/12 Masdiana Padaga 23
  24. 24. Chlamydospores are thick walled spores formed within a hyphae 03/04/12 Masdiana Padaga 24
  25. 25. Sporangiospores are formed within a sac (sporangium) at the end of an aerial hyphae called a sporangiophore 03/04/12 Masdiana Padaga 25
  26. 26. Sporangiospores 03/04/12 Masdiana Padaga 26
  27. 27. Conidiospores are produced in a chain at the end of a conidiophore. Unicellular conidiospores are called microconidia 03/04/12 Masdiana Padaga 27
  28. 28. Blastospores consist of a bud coming off the parental cell 03/04/12 Masdiana Padaga 28
  29. 29. NUTRITIONAL ADAPTATIONS OF FUNGIFungi absorb their food, rather than ingesting it.x Fungi grow better at a pH of 5, which is too acidic for most bacteria.x Almost all molds are aerobic. Most yeasts are facultative anaerobes.x Fungi are more resistant to high osmotic pressure than bacteria.x Fungi can grow on substances with very low moisture.x Fungi require less nitrogen than bacteria to grow.x Fungi can break down complex carbohydrates (wood, paper), that most bacteria cannot. 03/04/12 Masdiana Padaga 29
  30. 30. Fungi are classified based on thetype of sexual spore that theyform 03/04/12 Masdiana Padaga 30
  31. 31. Zygomycota Have non-septate Zygospores hyphea Have asexual sporangiospores Form sexual zygospores. They are large spores enclosed in a thick wall and formed from the fusion of two cells03/04/12 Masdiana Padaga 31
  32. 32. Ascomycota  Have septate Ascospores inside an hyphae ascus  Have asexual conidiospores  Have sexual ascospores. Ascospores result from the fusion of nuclei of two cells. They are produced in a sac-like structure called an ascus. 03/04/12 Masdiana Padaga 32
  33. 33.  Basidiomycota Have septate hyphae, asexual conidiospores Have sexual basidiospores. Basidiospores are formed externally on a base pedestal called a basidium Basidiospores 03/04/12 Masdiana Padaga 33
  34. 34. How do we identify molds in the lab?  Based on type of hyphae (septate versus non-septate)  Based on color of mycelium  Based on reproductive structures  Molds may form either sexual or asexual spores  Sexual spores are formed from the fusion of nuclei from two opposite mating strains of the same species. They are only formed under special conditions, but they are used to classify fungi (more on this later)  Asexual spores, which are most commonly used in identification, are formed by the aerial mycelium of a single organism by mitosis and cell division 03/04/12 Masdiana Padaga 34
  35. 35. ECONOMIC IMPORTANCE OF FUNGI 25-50% of harvested fruits and vegetables are damaged by fungi. Fungal infections of plants are commonly called rots, rusts, blights, wilts, and smuts. Phytophthora infestans: Caused great potato famine in mid-1800s. Over 1 million people died from starvation in Ireland. Many immigrated to the U.S.x Beneficial fungi: Candida oleophila: Prevents fungal growth on harvested fruits. Saccharomyces cerevisiae: Used to make bread and wine. Genetically engineered yeast strains are used to make proteins (Hepatitis B vaccine). Taxomyces: Produces anticancer drug taxol. Trichoderma: Produces cellulase. Used to make fruit juice. 03/04/12 Masdiana Padaga 35

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