Lecture Notes Flashcards
1
Q
What are fungi?
A
Filamentous eukaryotic, non-photosynthetic organisms that produce vegetative structures called hyphae which in mass form mycelial network
2
Q
The spores of the Asexual phase
A
Conidia
3
Q
What do Fungi need for growth?
A
Carbon, Nitrogen, Micronutrients, Vitamins, Oxygen, Moisture
Might need light
4
Q
Fungal Cell Wall Composition
A
Chitin microfibrils, Chitosan, B-linked glucans
Mannoproteins (form matrix throughout wall)
5
Q
Which Phyla produce visible structures?
A
Ascomycota and Basidiomycota
6
Q
Which Phyla produce microscopic structures?
A
Chytridiomycota, Glomeromycota, Zygomycota and Deuteromycota
7
Q
What does it mean to be heterotrophic?
A
Fungi that rely on carbon source produced by other organisms, not photosynthetic
8
Q
Phytopathogens
A
Infection of plants
9
Q
Entomopathogens
A
Infection of insects
10
Q
Aquatic pathogens
A
Infection of frog/fish
11
Q
Mycoparasites
A
Infection of other fungi
12
Q
Opportunistic Pathogens
A
Infection of humans
13
Q
Enzymes that destroy plant cell wall
A
Cellulase, pectinase, ligninase, hemi-cellulase
14
Q
Enzymes that break down proteins
A
Proteases
15
Q
Enzymes that destroy insects
A
Chitinase
16
Q
Enzymes that infect humans
A
Keratinase, protease, lipase, phospolipase
17
Q
How large can fungi get?
A
Armillaria ostoyae in Malheur National Forest in Oregon, 3.4 square miles
18
Q
What secondary metabolites do fungi produce?
A
Pigments (orange, red black)
Toxins (mycotoxins)
Organic acid (citric, oxalic)
Melanin (browns, blacks)
19
Q
After completing mycelial growth and spore production, many fungi produce secondary metabolites when?
A
After active growth slows doen and other staling products accumulate
20
Q
Conditions for growth
A
Temperature, moisture, appropriate nutrients, pH, oxygen and light
21
Q
COG: Temperature
A
15-25 degrees
Some less like snow mold (4 degrees)
Some higher like thermophilic fungi (35+)
22
Q
COG: Moisture
A
Absolute requirement for growth
23
Q
COG: Appropriate nutrients
A
Carbon source, Nitrogen source, elements like K and phosphorus, vitamins (E for cell membrane development)
24
Q
COG: pH
A
Range of 3-8, not great when super alkaline, produces pigments like citric acid
25
How do fungi survive?
As spores (short-lived), mycelium (rhizomorphs), chlamydospores, oospores and sclerotia
26
What is the best time for spores to be released?
Morning - early risers need drying conditions to release spores
Afternoon - need wind
Night - sensitive to UV like mushrooms
27
What three things reduce survival in nature?
1. Microbial competition
2. Depletion of nutrients
3. Adverse environment conditions (freezing, drouhgt, anaerobis conditions like flooding)
28
What are 5 ways that fungi spread?
1. Humans
2. Wind
3. Water
4. Insects
5. Fungal enhanced dispersal (shape of spores, etc)
29
Survival Lengths
Several hours - spores of mushrooms released at night, tiny, no pigments, sensitive to UV
Several days - spores of most fungi, pigmented survive longer
Few weeks - mycelium organized into strands (rhizomorph (root) form strands)
Several months - thick walled spores (chlamydospores or oospores)
Many years - Sclerotia (20-30 years)
30
8 parts of Good Fungi
1. Nutrient cycling
2. Fungi as food
3. Fungi as fermentation
4. Fungal enzymes for industrial uses
5. Ant-associated fungi
6. Decontamination of soils by fungi
7. Fungi attacking insects
8. Fungi infecting Fungi
31
Nutrient Cycling and Ecology Preservation
Break down plant material, recycling carbon and nitrogen.
Composts have high fungal activity like bacteria, enzymes act on plant material and digest cellulose and lignin to obtain sugars and other small compounds.
Eg. Dung fungi liks aspergillus
32
Fungi as Food
Soybean fermentation via aspergillus or rhizopus for shoyu or tempeh
Milk and cheese via penicillium
Secretes enzymes, degrades fats and proteins (lipolytic and proteolytic enzymes), releases methyl ketones that make unique flavours
Wine via botrytis
33
Fungal enzymes for Industrial Uses
Reducing pulp and other waste in paper production. Fungal enzymes eg. Cellulase
Reducing agricultural/municipal wastes during composting
Enzymes added to laundry detergent to break down food particles and remove stains like cellulase
Enzymes in biofuel production like Fusarium on corn converts xylose to ethanol
34
Ant-associated fungi
Ant-fungus mutualism is symbiosis; ants actively cultivate fungus much like humans grow crops as food. The leaf cutter ant is a well known example of this symbiosis and a mutualism with fungi is also noted in some species of termites in Africa
35
Decontamination of Soil by Fungi
Fungi can degrade hydrocarbons, pesticides, pollutants, dyes and heavy metals via biotransformation
Requires the presence of enzyme P450 monooxygenase
36
Fungi attacking Insects
These entomopathofens are used as benefitial to fungi to infect and kill insects like aphids and beetles
Fungi include Beauvaria bassinae and Verticillium lecanii which penetrate the insect cuticle, secrete chitinases and grow - Biopesticides
37
Fungi infecting Fungi (mycoparasites)
Produce enzymes that destroy the cell walls of other fungi (chitinases, glucanases) and produce antibiotics such as Trichoderma, Gliocladium, Penicillium
Some fungi that attack mushrooms are considered detrimental (green mould Trichoderma)
38
Bad Fungi (general)
Fungi cause infection and death of many plant species (phytopathogens)
They secrete enzymes (pectinase, cellulase) as well as toxins that kill plant cells (nectrotrophic fungi)
Some fungi have specialized methods for infection but instead take up nutrients (obligate parasites or biotrophs) like powdery mildew or rust fungi
39
6 parts of Bad Fungi
```
Impact of Plant Disease
Fungi of historical importance (potato blight)
Necrotrophic fungi
Biotrophic fungi
Fungal destruction of wood and paper
Fungi causing allergies
```
40
Impacts on Plant Diseases
Over 100 000 diseases affect plants, up to 20% of agricultural produce can by lost due to fungal pathogens
Diseases can result in the higher use of fungicides to manage them
41
Fungi of Historical Importance
Late Blight on the potatoes via Phytophthora infestans
Ergot on rye via Claviceps purpurea caused St. Anthony’s fire, produced alkaloid mycotoxins including lysergic acid derivative
42
Necrotrophic Fungi
Can grow on dead or living plant material
Produce enzymes and toxins that destroy plant cells
Can affect a broad range of plant species (up to 400 species of plants for Botrytis cinerea)
Root rot, fruit rot, via Pythium, Fusarium, Rhizoctonia
43
Biotrophic Fungi
Can only grow on living plant cells, don’t produce toxins that destroy cells, infect by penetration peg and haustorium to absorb nutirents
Usually infect 2-3 species, specialized pathogens
Powdery mildew and rust fungi
Can survive as mycelium or spores in absence of host but not for long
44
Fungal Destruction of Wood and Paper
Due to the production of enzymes that destroy plant cells, fungi can be a problem that affects the storage of wood or paper
45
Fungi causing Allergies
Spore production by fungi can be in the millions
Fungi such as Cladosporium, Alternaria, Aspergillus are common in air during spring/ summer
Black mold by Stachybotris
46
Ugly Fungi
Fungi can produce toxins/mycotoxins that are harmful to humans and animals, these are secondary metabolic products produced after the fungus has reached maximum growth
Eg. Fusarium, Penicillium, Aspergillus, Stachybotrys, Alternaria
47
Mycotoxins
Toxigenic and carcinogenic, includes cyclopeptides, alkaloids, coumarins
Toxic at low concentrations 1ug/kg body mass
Prevalent in food, heat stable
48
Examples of Mycotoxins
Aflatoxins by Aspergillus (mouldy peanuts)
- Ingestion may result in conversion to more toxic metabolites
Trichothecenes by Fusarium; vomitoxin, zearalenone on wheat/ barley)
Ochratoxins produced by Penicillium and Aspergillus
49
Skin Infections (dermatitis)
Fungi that grow on skin are called Dermatophytes
Fungi produce proteases and peptidases that break down keratin found in skin and hair. The tissue respond by producing more cells which are used by fungus to grow. Itchiness, mycoses.
50
Ringworm Fungi
Naturally occurring fungi in soil that infect skin of animals, can break down feathers, nails, hooves of dead animals recycling nutrients
51
Chytridiomycosis in Frogs
Opportunistic fungi that can grow 38-40 degrees and infect humans with weakened immune system
Aspergillus fumigatus causes aspergillosis disease of lungs, found in soil, composts, decaying plants
Spores germinate on lung tissues, invade the alveoli, produce virulence factors that can overcome weakened immune systems
52
3 things a DNA region should have to be a successful barcode
1. Region highly variable between species
2. Primer binding sites are conserved, not variable
3. Region is present in large number in genome
53
Advantages and Limitations of ITS region to identify a fungus to species
Fast, easy to perform, standard in mycology, can be used in semi-degraded samples
Some very closely related have identical ITS regions, cannot tell these apart using ITS PCR
54
Anamorph
Asexual state
55
Telemorph
Sexual state
56
Holomorph
Whole fungus, both states
57
Why is Deuteromycota taxinomically incorrect?
Many common molds, no common sexual stage (lost or not observed)
Polyphyletic group! Not legitimate phylum
58
Advantages and Disadvantages of Teleomorph name
Taxonomically correct, fits well into phylogenetic species concepts
Can be extremely uncommon to observe, not as well known
59
Advantages and Disadvantages of Anamorph Name
More common state, well known
Not taxonomically correct, deuteromycota not legitimate
60
Zygomycota fungi - definition and examples
Spores produced from sporangiophores
Mucor racemosus, rhizopus stolonifer
61
Oomycota - definition and examples
Sporangiospores and oospores present
Pythium irregulare
62
Ascomycota - definition and examples
Ascospores produced within an ascus
Chaetomium globosum, sordaria fimicola
