Microbiology UNIT 5: Fungi

Microbiology and Parasitology

UNIT 5: FUNGI

Microbiology

Virus: Ebola

Bacteria: Salmonella

?ENEMY OR… …FRIEND

Fungi: Mushroom

Algae: Algal bloom

Test your memory

A. True or False1. A Virus has no cell and is therefore depedent on host cells2. No organism is safe from viral infections3. Viruses contain at least a genome, capsid and envelope4. All obligate intracellular pathogens are viruses5. Viroids are infectious RNA molecules

B. Multiple choice1. Which event can trigger a latent virus infection

a) Sleeping; b) Cold drink; c) Excessive sunlight

2. The release of an enveloped virus particle from a host cell is calleda) Budding; b) Lysis; c) Escape

3. Which statement about replication of bacteriophages is falsea) It takes approximately 30 min to replicate; b) Replication takes place via the lytic cyle; c) The bacteriophages enter the host cell

Growth

EXPERIMENT 001Title: Potato germsTopic: Growth of bacteria

1. Peel and slice potato (with gloves) in 4 pieces of equal size

2. Put one slice (with gloves) in box labeled “control”

3. Put second slice (with gloves) in box labeled “oral” and cough/blow on it

4. Take third slice and rub it on the table before putting it in box labeled “table”

5. Take out your gloves and rub fourth slice with your hands before putting it in box labaled “hands”

What’s happening?

• Explain the difference in bacterial growth on the samples – When using gloves, the potato does not get contaminated with germs– Therefore, “control” shows only few bacterial growth– The contaminated samples show more bacterial growth

• At what other places, apart from the human body, bacteria can be found? – Everywhere on Earth: in soil, in water, on plants, even in radioactive waste

• Do all bacteria cause disease? – No, some bacteria are even beneficial to us– They can inhibit the growth of disease-causing

microorganisms (pathogens)

Variety of Microbes

• Categories– Acellar: Viroids, Virus, Prion– Prokaryotes (cellular without nucleus): Bacteria, Archaea, Cyanobacteria– Eukaryotes (cellular with nucleus): Algae, Fungi, Protozoa

Microbes

Acellular ViroidsPrions

Virusus

Cellular

ProkaryotesArchaeaBacteria

Cyanobacteria

EukaryotesAlgaeFungi

Protozoa

Today

• Fungi• Structure

– Cells– Shape– Size

• Reproduction• Classification

– Yeasts– Moulds– Fleshy fungi

• Medical signficance• Summary

Fungi

• Study of fungi– Mycology: mycologist

• Everywhere– Saprophytic (in water and soil)– Parasitic (on/in animals and plants)– Harmful/unpleasant

• Fungal diseases• Spoilage of food

– Beneficial• Food and drinks• Drugs

• No plants– Not photosynthetic

Burton’s Microbiology: Chapter 4

Saprophytes

• Garbage disposers– Main source of food: dead/decaying organic matter– Decompose material into absorabable nutrients: “recyclers”– No fungi means endless piles of plant and animal waste!


Eucaroytic cells

• Fungi: Eucaroytic cell– Cell envelope

• Cell membrane• Cell wall (chitin)

– Nucleus with chromosome– Cytoplasm

• Endoplasmic reticulum• Ribosomes• Golgi Complex• Mitochondria

– Flagella? (rare)


Difference with procaryotes:10x larger than bacteria cellContains “true nucleus”

Cell envelope


• Cell membrane– Flexible thin skin that encloses the cells

interior– Controls in/out transport of substances

(via proteins in membrane)

• Cell wall– Provide rigidity, strength and protection– Much simpler in structure than bacterial

cell walls– Cell walls of fungi contain polysaccharide

(chitin): also found in exoskeletons of crabs

Nucleus

• Primary difference between procaryotes and eucaryotes!

• Command center– controls the functions of entire cell

• Three components– Nucleoplasm (matrix)– Chromosome

• Linear DNA molecules (genes: genetic information)

• Proteins– Nuclear membrane (with pores)


Cytoplasm

• Semifluid matrix with cytoplasmic organelles having specific functions

– Endoplasmic reticulum (ER)• Surface for ribosomes to attach

– Ribosomes• Sites for protein synthesis

– Golgi Complex• Packaging plants: transform

synthesized proteins into functional ones and package them

– Mitochondria• Power plants: produce energy to drive

cellular functions


Structure of fungi

Unicellar Filaments (hyphae mycelium)


Cytoplasm divided

Cytoplasm multinucleated

Size of fungi


• Typical size– Yeast: diameter of 3-5 μm (1 million micrometers = 1 meter) – Septate hyphae: width of 2-15 μm (and become very large in length)– Aseptate hyphae: width of 10-30 μm (and become very large in length)

Microscopic appearance


Reproduction (1)

• Budding – Asexual– Bud grows on parent cell– Nucleus divides and one of the nuclei

passes into daughter cell (bud)– Bud separates from parent cell

• Fragmentation– Asexual– Hyphae separate into pieces– Each component grows as separate entity


Reproduction (2)

• Formation of spores– Sexual spores

• Fusion of two nuclei– Asexual spores (conidia)

• No fusion of nuclei

• Fungal spores– Very resistant structures

• Resistant to heat, cold, acids, bases, etc.– Carried great distances by wind– Many people allergic


Microbial classification

• Taxonomy– Kingdom of Fungi

• Divided in five phyla

• Three important types– Yeasts– Moulds– Fleshy fungi


Food spoilageWater mouldsPlant diseases

MushroomsPenicillium

Yeasts

• Single-celled (unicellular), no hyphae– Individual cells:

blastospores / blastoconidia• Reproduction

– Budding (majority)– Spore formation

• Presence– Soil / water– Fruits / vegetables

• Fermentation (Louis Pasteur) by yeast– Anaerobe: Sugar alcohol (wine and beer)– Aerobe: Sugar CO2 + water (bread)

• Pathogens– Candida


Yeast colonies

Cocci

Budding yeast (oval)

Growth

EXPERIMENT 002Title: Bubbly yeastTopic: Growth of yeast

1. Mix the yeast and sugar with some warm water and stir in a bowl

2. Pour the mixture into the bottle and cover the bottle with a balloon

3. Put the bottle on top of a heater and observe the balloon

4. Repeat the procedure without adding sugar to the yeast.

What’s happening?

• What does yeast need to grow?– Sugar is the source of energy

• What causes the balloon to blow? – Yeast breaks down sugar to ethanol (alcohol) and carbon dioxide– Process is known as fermentation: production of bread, beer and wine– Carbon dioxide released from the fermentation process is filling balloon– When making bread: CO2 causes dough to rise to make a light spongy loaf

– In the absence of sugar, yeast lost its source of energy: no CO2 is produced

Moulds

• Filaments (Hyphae mycelium)– Aerial hyphae– Vegetative hyphae

• Reproduction– Spore formation (sexually or asexually)

• Presence– Soil / water– Food spoilage (bread moulds, potato blight)– Food flavor (cheese)

• Produce– Antibiotics (Penicillium)– Enzymes and acids


Bread moulds

Fleshy fungi

• Large fungi – Forest: mushrooms, toadstools,

puffballs, bracket fungi– No microorganisms!

• Structure– Network of filaments (mycelium)

• In soil or rotting log– Fruiting body

• Spore formation and release• Spore germinates into new organism

• Delicious food vs. toxic death


Medical significance

• Fungi that cause disease (pathogens)– Plants

• Moulds: blights or rusts– Humans / animals (inhalation, wounds)

• Microbial intoxication: mycotoxins• Infectious disease: mycoses


Mycoses

• Superficial– Hair, nails, dead skin layers (epidermis)– e.g. toenail infections

• Cutaneous– Living layers of skin (dermis)– Mouth, skin, vagina infections (candida yeasts)

• Subcutaneous– Dermis and underlying tissues– e.g. Madura foot

• Systemic– Internal organs– Infections of lungs, bloodstream, nervous system


Diagnosis & treatment

• Identification of yeasts– Culturing (biochemical tests)

• Identification of moulds– Macroscopic observation

• Color, texture, topography, growth– Microscopic observation

• Structure of spores– Skin tests

• Treatment– Antifungal agents

• Nystatin, amphotericin, fluorocytosine• Caution: “toxic”


Yeasts

Moulds

Dimorphic fungi

• Dimorphism– In vivo (37 °C): yeasts– In vitro (25 °C): moulds

• Pathogenic– Skin disease– Lung infection


Lichens

• Colored (circular) patches– On tree trunks and rocks– Gray, brown, black, orange, green, etc.– Leaflike, crustlie, shrubby, gelatinous

• Symbiotic relationship– Alga / cyanobacterium (photobiont)– Fungus (mycobiont)

• Mutualism– Both parties benefit

• Antibacterial properties


Slime moulds


Combination of fungi and

protozoa

Very interesting life cycle

Cell differentation at lowest level

Summary

Bacteria Viruses Fungi

Cell structure No nucleusComplex cell wall

-(dependent on host cell)

True nucleusSimple cell wall (chitin)

Reproduction Binary Fission(asexual)

Replication(asexual)

BuddingFragmentationSpore release (sexual/asexual)

Structure SphericalRodsSpirals

Spherical / PolyhedralHelicalComplex

Spherical (oval)Filaments

Size 1-3 μm 0.01-0.3 μm 3-30 μm

Study Bacteriology Virology Mycology

Pathogenic Yes Yes Yes

Burton’s Microbiology: Chapter 2,3,4

The End

Test your memory

A. True or False1. Fungi are, like plants, photosynthetic organisms2. Unlike any other microbe, the cell walls of fungi are composed of chitin3. Dimorphic microbes are a combination of algae and fungi4. Fermentation of yeast is used to produce blue cheese5. Fungi can cause both intoxinations and infectious diseases

B. Multiple choice1. Reproduction of fungi can be

a) Asexual only; b) Sexual only; c) Both asexual and sexual

2. Sexual spores are produced bya) A process called conidia; b) Budding; c) The fusion of nuclei

3. The most dangereous form of mycoses isa) Systemic; b) Superficial; c) Cutaneous

Microbiology UNIT 5: Fungi

Education

Transcript of Microbiology UNIT 5: Fungi