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1
SCOPE AND HISTORY OF
MICROBIOLOGY
CHAPTER 1
Why Study Microbiology?

Ubiquity
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Microbes in Our Lives

Microorganisms are organisms that
are too small to be seen with the
unaided eye.
 “Germ” refers to a rapidly growing
cell.
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Why Study Microbiology?

Biological roles- decomposers, recyclers, symbionts
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Animal digestion - ruminants, methane
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Food Microbiology - yogurt, sauerkraut, Kim
Chee, cheese, beer, bread etc.
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Food safety - prevent putrefication, disease etc.
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Why Study Microbiology?

Pharmaceuticals- produce complex drug
molecules. (ex. insulin )
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Bioremediation - using microbes to clean
pollution
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Pathogenicity - bacteria and viruses that make us
sick
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Fundamental Biology most biochemical
pathways worked out with microbes
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Microbes in Research
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Simple structure- many are prokaryotic
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Large populations - up to billions/ml
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Rapid growth rates
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Vibrio harveyii = fastest grower known
1 gen/15 mins
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Scale of Microbes
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Classification of Microorganisms
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Three domains
– Bacteria
– Archaea
– Eukarya
• Protists
• Fungi
• Plants
• Animals
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Microbe Types

Bacteria
prokaryotes
Eubacteria
Archaebacteria
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Bacteria

Prokaryotes
 Peptidoglycan
cell walls
 Binary fission
 For energy, use
organic
chemicals,
inorganic
chemicals, or
photosynthesis
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Figure 1.1a
Archaea:

Prokaryotic
 Lack peptidoglycan
 Live in extreme
environments
 Include:
– Methanogens
– Extreme halophiles
– Extreme thermophiles
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Figure 4.5b
Microbe Types

Algae
Protista, Planta

Fungi
Eukaryotes
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Algae

Eukaryotes
 Cellulose cell walls
 Use photosynthesis
for energy
 Produce molecular
oxygen and organic
compounds
Volvox
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Figure 1.1d
Fungi
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Eukaryotes
Chitin cell walls
Use organic chemicals
for energy
Molds and mushrooms
are multicellular
consisting of masses of
mycelia, which are
composed of filaments
called hyphae
Yeasts are unicellular
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Figure 1.1b
Microbe Types

Viruses
Living?
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Microbe Types

Protozoa
eukaryotes
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Protozoa

Eukaryotes
 Absorb or ingest
organic chemicals
 May be motile via
pseudopods, cilia, or
flagella
Amoeba
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Figure 1.1c
Microbe Types

Helminths/Arthropods
Eukaryotes (multicellular)
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Multicellular Animal Parasites

Eukaryote
 Multicellular
animals
 Parasitic
flatworms and
round worms are
called helminths.
 Microscopic
stages in life
cycles.
tapeworm
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Figure 12.28
Microorganisms:
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Figure 1.1
Roles of Microbiologists
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Biological
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Pharmaceutical/Vaccines
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Agricultural- Rumen microbiology
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Microbiology Settings
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Universities
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Commercial
laboratories

food prep &
cosmetics
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Microbiology Settings

Legal
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Clinical
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Microbiology Settings

Public Health
 Epidemiology
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Microbiology History

Plagues in History
http://www.oddee.com/item_90608.aspx
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The Black Plaque-Bubonic plaque
1348 and 1350 (1340 - 1771)
Killed 75 million people worldwide
Yersinia pestis
Flea vector.
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Smallpox
(430 BC? - 1979):
Killed more than 300 million people worldwide in the 20th century alone,
and most of the native inhabitants of the Americas.
Smallpox (also known by the Latin names Variola or Variola vera) is a
contagious disease unique to humans. Smallpox is caused by either of two
virus variants named Variola major and Variola minor. The deadlier form, V.
major, has a mortality rate of 30–35%, while V. minor causes a milder form
of disease called alastrim and kills ~1% of its victims. Long-term sideeffects for survivors include the characteristic skin scars. Occasional side
effects include blindness due to corneal ulcerations and infertility in male
survivors.
Smallpox killed an estimated 60 million Europeans, including five
reigning European monarchs, in the 18th century alone. Up to 30% of those
infected, including 80% of the children under 5 years of age, died from the
disease, and one third of the survivors became blind.
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Microbiology History

Early Studies
– Hooke Cork Slices- 1st Scope (cell)
– Van Leeuwenhoek microscope
– Linnaeus classification
– Schwann
cell theory
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Fig. 1-9
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Fig. 1-10
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Germ Theory vs. Spontaneous
Generation

Redi
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http://en.wikipedia.org/wiki/Francesco_Redi

Spallanzani - boiling
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http://en.wikipedia.org/wiki/Lazzaro_Spallanzani
-
maggots
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Germ Theory vs. Spontaneous
Generation

Pasteur
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http://en.wikipedia.org/wiki/Louis_Pasteur
Understanding Disease

Robert Koch
 Koch’s
postulates
http://en.wikipedia.org/wiki/Robert_Koch

Lister/
disinfection
Semmelweiss
handwashing
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Koch’s postulates
1. The suspected causal organism must be constantly associated with the disease.
2. The suspected causal organism must be isolated from an infected plant (or animals)
and grown in pure culture.
3. When a healthy susceptible host is inoculated with the pathogen from pure culture,
symptoms of the original disease must develop.
4. The same pathogen must be re-isolated from plants (animals) infected under experimental
conditions.
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Special Fields of Study

Immunology
Immune system and it’s interaction with microbes

Virology
Study of very small ?living? Viral particles
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Special Fields of Study

Chemotherapy
– Antibiotics
Natural products
penicillin
– Synthetics
Man-made
Erhlich
doxycycline
Alexander Fleming
Penicillin
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Special fields of Study

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
Genetics/Molecular Biology
genes and how they are expressed
Recombinant DNA technology
– Genomics
decyphering genomes and expression
– Proteomics decyphering protein structure/function
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Microbes I know and Love?
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Bacillus megaterium
Klebsiella aerogenes
Escherichia coli
Klebsiella pneumoniae
Mycobacterium smegmatis
Mycobacterium marinum
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A Brief History of
Microbiology

Ancestors of bacteria were the first
life on Earth.
 The first microbes were observed in
1673.

http://en.wikipedia.org/wiki/Antonie_van_Leeuwenhoek
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The First Observations

In 1665, Robert Hooke reported that living
things were composed of little boxes or cells.
 In 1858, Rudolf Virchow said cells arise from
preexisting cells.
 Cell Theory. All living things are composed of
cells and come from preexisting cells
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The Golden Age of
Microbiology

1857-1914
 Beginning with Pasteur’s work,
discoveries included the relationship
between microbes and disease,
immunity, and antimicrobial drugs
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Fermentation and Pasteurization

Pasteur showed that microbes are responsible
for fermentation.
 Fermentation is the conversation of sugar to
alcohol to make beer and wine.
 Microbial growth is also responsible for
spoilage of food.
 Bacteria that use alcohol and produce acetic
acid spoil wine by turning it to vinegar (acetic
acid).
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Fermentation and Pasteurization

Pasteur demonstrated that
these spoilage bacteria
could be killed by heat that
was not hot enough to
evaporate the alcohol in
wine. This application of a
high heat for a short time
is called pasteurization.
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Figure 1.4
The Germ Theory of Disease

1835: Agostino Bassi showed a silkworm
disease was caused by a fungus.
 1865: Pasteur believed that another silkworm
disease was caused by a protozoan.
 1840s: Ignaz Semmelweiss advocated
handwashing to prevent transmission of
puerperal fever from one OB patient to another.
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The Germ Theory of Disease

1860s: Joseph Lister used a chemical
disinfectant to prevent surgical wound
infections after looking at Pasteur’s work
showing microbes are in the air, can spoil food,
and cause animal diseases.
 1876: Robert Koch provided proof that a
bacterium causes anthrax and provided the
experimental steps, Koch’s postulates, used to
prove that a specific microbe causes a specific
disease.
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Vaccination

1796: Edward Jenner inoculated a person
with cowpox virus. The person was then
protected from smallpox.
 Called vaccination from vacca for cow
 The protection is called immunity
47
The Birth of Modern
Chemotherapy
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Treatment with chemicals is chemotherapy.
Chemotherapeutic agents used to treat
infectious disease can be synthetic drugs or
antibiotics.
Antibiotics are chemicals produced by bacteria
and fungi that inhibit or kill other microbes.
Quinine from tree bark was long used to treat
malaria.
1910: Paul Ehrlich developed a synthetic
arsenic drug, salvarsan, to treat syphilis.
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1930s: Sulfonamides were synthesized.
The Birth of Modern
Chemotherapy

1928: Alexander
Fleming discovered
the first antibiotic.
 He observed that
Penicillium fungus
made an antibiotic,
penicillin, that killed
S. aureus.
 1940s: Penicillin was
tested clinically and
mass produced.
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Figure 1.5
Modern Developments in
Microbiology

Bacteriology is the study of bacteria.
 Mycology is the study of fungi.
 Parasitology is the study of protozoa and
parasitic worms.
 Recent advances in genomics, the study of an
organism’s genes, have provided new tools for
classifying microorganisms.
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Modern Developments in
Microbiology

Immunology is the study
of immunity. Vaccines and
interferons are being
investigated to prevent
and cure viral diseases.
 The use of immunology to
identify some bacteria
according to serotypes
(variants within a species)
was proposed by Rebecca
Lancefield in 1933.
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Modern Developments in
Microbiology

Virology is the study of viruses.
 Recombinant DNA is DNA made from two
different sources. In the 1960s, Paul Berg
inserted animal DNA into bacterial DNA and the
bacteria produced an animal protein.
 Recombinant DNA technology or genetic
engineering involves microbial genetics and
molecular biology.
52
Modern Developments in
Microbiology

Using microbes
– George Beadle and Edward Tatum showed that
genes encode a cell’s enzymes (1942)
– Oswald Avery, Colin MacLeod, and Maclyn McCarty
showed that DNA was the hereditary material (1944).
– Francois Jacob and Jacques Monod discovered the
role of mRNA in protein synthesis (1961).
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Selected Novel Prizes in
Physiology or Medicine
1901*
von Behring
Diphtheria antitoxin
1902
Ross
Malaria transmission
1905
Koch
TB bacterium
1908
Metchnikoff
Phagocytes
1945
Fleming, Chain, Florey
Penicillin
1952
Waksman
Streptomycin
1969
Delbrück, Hershey, Luria
Viral replication
1987
Tonegawa
Antibody genetics
1997
Prusiner
Prions
* The first Nobel Prize in Physiology or Medicine.
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