Microbial World and You
What did the male bacteria say to the female
bacteria?
Who needs biology when we have chemistry.
What is Microbiology?
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Micro - too small to be seen with the naked
eye
Bio - life
ology - study of
Organisms included in the study
of Microbiology

1. Bacteria
• Bacteriology

2. Protozoans
• Protozoology

3. Algae
• Phycology

4. Parasites
• Parasitology

5. Yeasts and Molds
• Mycology
• Fungi

6. Viruses
• Virology
5 Characteristics of Life

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1. Cells
2. Maintain structure by taking up
chemicals and energy from the environment
3. Respond to stimuli in the external
environment
4. Reproduce and pass on their organization
to their offspring
5. Evolve and adapt to the environment
Physical Requirements

Temperature
• psychrophiles (cold loving microbes)
• range
0 C - 20 C
• mesophiles (moderate temp. loving microbes)
• range
• thermophiles
• range
20 C - 40 C
(heat loving microbes)
40 C - 100 C
pH

Most bacteria grow between pH 6.5 - pH 7.5

Very few can grow at below pH 4.0
• many foods, such as sauerkraut, pickles, and cheeses
are preserved from spoilage by acids produced during
fermentation
Bacterial Growth - increase in the # of
cells

Binary Fission

Generation Time (Doubling Time)
• time required for a cell to divide
• most about 1 Hr. To 3 Hrs.
• E. coli - 20 minutes
• Mycobacterium tuberculosis - 24 Hrs.
Binary Fission - unchecked


E. coli - generation time of 20 min.
20 generations (about 7 hrs.)
• 1 million cells

30 generations ( about 10 hrs.)
• 1 billion cells

72 generations ( about 24 hrs.)
• 1 x 1021
• 1,000,000,000,000,000,000,000
cells
Limiting factors in the
environment
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Lack of food, water or nutrients
space
accumulation of metabolic wastes
lack of oxygen
changes in pH
temperature
Phases of Growth

4 Phases

1. Lag Phase
2. Log Phase
3. Stationary Phase
4. Death Phase
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1. Lag Phase
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Bacteria are first introduced into an
environment or media
Bacteria are “checking out” their
surroundings
cells are very active metabolically
# of cells changes very little
1 hour to several days
2. Log Phase
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Rapid cell growth (exponential growth)
population doubles every generation
microbes are sensitive to adverse conditions
• antibiotics
• anti-microbial agents
3. Stationary Phase


Death rate = rate of reproduction
cells begin to encounter environmental
stress
•
•
•
•
•
•
lack of nutrients
lack of water
not enough space
metabolic wastes
oxygen
pH
Endospores would form now
4. Death Phase

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Death rate > rate of reproduction
Due to limiting factors in the environment
Bacteria - what comes to mind?
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Diseases
Infections
Epidemics
Food Spoilage
When in fact…
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Only 1% of all known bacteria cause
human diseases
About 4% of all known bacteria cause
plant diseases

95% of known bacteria are nonpathogens

http://www.youtube.com/watch?v=IekdfJ7Zyk&safety_mode=true&persist_safety_mode=1&safe=active
Microbes Benefit Humans

1.Bacteria are primary decomposers recycle nutrients back into the environment
(sewage treatment plants)
They produce various food products
• cheese, pickles,
sauerkraut, green
olives
• yogurt, soy sauce,
vinegar, bread
• Beer, Wine, Alcohol
3. Microbes are used to produce Antibiotics

Penicillin

Mold
• Penicillium notatum

1928 Alexander Fleming
4. Bacteria synthesize chemicals that our
body needs, but cannot synthesize

Example: E. coli
• B vitamins - for metabolism
• Vitamin K - blood clotting

Escherichia coli
• Dr. Escherich
• Colon (intestine)
5. Competitive Exclusion

Our normal microbial flora prevents
potential pathogens from gaining access to
our body
6. Bioremediation


Using microbes to clean up pollutants and
toxic wastes
Exxon Valdez - 1989

2 Genera
• Pseudomonas sp.
• Bacillus sp.
7. Recombinant DNA Technology
Gene Therapy
Genetic Engineering

Bacteria can be manipulated to
produce enzymes and proteins they
normally would not produce
• Insulin
• Human Growth Hormone
• Interferon
8. Microbes form the basis of the
food chain

Marine and fresh
water microorganisms
http://www.youtube.com/watch?v=THRgkllfj1A&safety_mode
=true&persist_safety_mode=1&safe=active
Microbes do benefit us, but they are also
capable of causing many diseases
*+Pneumonia *Whooping Cough
*Botulism
*Typhoid Fever +Measles
*Cholera
*Scarlet Fever +Mumps
*Syphilis
*Gonorrhea
+Herpes 1
*Chlamydia
*Tuberculosis
+Herpes 2
*+Meningitis
*Tetanus
+RSV
*Strep Throat *Lyme Disease +AIDS
*Black Plague *+Diarrhea
*Gangrene
* = bacteria, + = virus
Spontaneous Generation

Theory that life just “spontaneously”
developed from non-living matter

Example:
• toads, snakes and mice - moist soil
• flies and maggots - manure and decaying flesh
Experiments to disprove Spontaneous
Generation

Francesco Redi
1668

Rudolph Virchow 1858
• Theory of Biogenesis
• Cells can only arise from preexisting cells

Louis Pasteur
1861
Pasteur designed special “swan-necked flasks”
with a boiled meat infusion
Shape of flask allowed air in (vital force) but trapped
dust particles which may contain microbes
Germ Theory of Disease
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Hard for people to believe that diseases
were caused by tiny invisible “wee
animalcules”
Diseases, they thought, were caused by:
•
•
•
•
•
•
demons
witchcraft
bad luck
the wrath of God
curses
evil spirits
Koch’s Postulates

1. The same organisms must be found in all cases of a given
disease.
 2. The organism must be isolated and grown in pure culture.
 3. The isolated organism must reproduce the same disease
when inoculated into a healthy susceptible animal.
 4. The original organism must again be isolated from the
experimentally
infected animal.
Exceptions to Koch’s Postulates
Mycobacterium leprae
Leprosy
Never been grown in pure culture on artificial media
Koch established the Microbial
Origins of 3 important diseases
of his day
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1. Cholera (fecal-oral disease)
• Vibrio cholerae
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2. Tuberculosis (pulmonary infection)
• Mycobacterium tuberculosis

3. Anthrax (sheep and cattle)
• Bacillus anthracis
Golden Age of Microbiology

1857 - 1914
Pasteur
• Pasteurization
• Fermentation

Joseph Lister
• Phenol to treat surgical wounds – 1st attempt to control infections
caused by microoganisms

Robert Koch
• Koch’s Postulates
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Edward Jenner
• vaccination

Paul Erlich
• 1st synthetic drug used to treat infections
• Salvarsan - arsenic based chemical to treat Syphilis
• “salvation” from Syphilis
Bacterial Morphology
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Bacilli
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Cocci
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Spiral
Arrangements
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Diplo
Strepto
Staphylo
Tetrad
Vibrio
bacter
bacterium
comma shaped
bacilli
bacilli
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Staphylococcus aureus
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Staphylococcus
epidermidis
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Streptococcus
pneumoniae
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Vibrio cholerae
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Rhodospirillium
rubrum
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Bacillus subtilis
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Micrococcus luteus
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Bacillus anthrasis
Streptococcus
pyogenes
Steptococcus lactis
Streptococcus faecalis
Campylobacter jujuni
Helicobacter pylori
Enterobacter
aerogenes