Microbiology
An Evolving Science
Second Edition
Joan Slonczewski and John Foster
1
Microbial Life:
Origin and
Discovery
PowerPoint® Lecture Outlines
Prepared by Johnny El-Rady, University of South Florida
Copyright © 2010 W. W. Norton & Company, Inc. Permission required for reproduction or display
Chapter Overview
What is a microbe?
● How microbes have shaped human history
● The development of medical microbiology
● The development of microbial ecology
● The microbial family tree in all its splendor
● The advent of cell biology and the brilliant
DNA revolution
●
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What Is a Microbe?
A microbe is a living organism that requires
a microscope to be seen.
- Microbial cells range in size from
millimeters (mm) to 0.2 micrometer (mm).
- Viruses may be 10 times smaller.
Some microbes consist of a single cell.
Each microbe contains in its genome the
capacity to reproduce its own kind.
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Representative Microbes
Figure 1.2
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What Is a Microbe?
The simple definition of a microbe, however,
leaves us with contradictions.
1. Supersize microbial cells
- e.g.: Thiomargarita namibiensis
2. Microbial communities
- e.g.: Biofilms
3. Viruses
- e.g.: Mimivirus
The largest prokaryote, Thiomargarita namibiensis
compared to a fruit fly,
Drosophila. A single cell can reach a diameter
of 0.75
Figure
1.1
mm. Thiomargarita namibiensis, which means 'sulfur
pearl from Namibia
Figure 1.4
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Thiomargarita namibiensis is found in the sulfur-rich sediments of the ocean
floor along the west coast of Africa, where they play an important ecological
role. By oxidizing sulfur they act as detoxifiers, removing the poisonous gas
from the water and keeping it hospitable for the fish and other marine
organisms.
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Microbes include members of the three
domains of life.
Figure 1.5
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Microbial Genomes Are Sequenced
A genome is the total genetic information
contained in an organism’s chromosomal DNA.
The first genome sequenced was that of a virus,
bacteriophage fX174.
Nearly two decades passed before the first
genome sequence of a cellular microbe was
completed – Haemophilus influenzae.
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Figure 1.8
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Microbes Shape Human History
Microbes have shaped human culture since
our earliest civilizations.
- Yeasts and bacteria = Foods and
beverages
- “Rock-eating” bacteria = Lithotrophs
enabled mining of metals
- Unfortunately, they also consume
stones of ancient monuments.
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Cement degrading bacteria
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Figure 1.9
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Microbial Diseases
Throughout history, microbial diseases have
profoundly affected human demographics and
cultural practices.
- 14th century = Bubonic plague caused by
Yersinia pestis
- 19th century = Tuberculosis caused by
Mycobacterium tuberculosis
- Today = Acquired immunodeficiency syndrome
(AIDS) caused by the human immunodeficiency
virus (HIV)
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Medieval church procession to ward
off the Black Death (bubonic
plague)
The AIDs Memorial Quilt
Figure 1.10
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Discovery of Microbes
Robert Hooke (1635–1703)
- Built the first compound microscope
- Used it to observe mold
Figure 1.12
- Published Micrographia,
the first manuscript that
illustrated objects under
the microscope
- Coined the term cell
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Discovery of Microbes
Antoni van Leeuwenhoek (1632–1723)
- A cloth draper
- Built single-lens magnifiers, complete with
sample holder and focus adjustment
- First to observe single-celled microbes
- He called them “small animals.”
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Figure 1.13
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Do Microbes Have Parents?
Spontaneous generation = The theory that
living creatures could arise without parents
Francesco Redi (1660s) = Showed that
maggots in decaying meat were the
offspring of flies
Lazzaro Spallanzani (1760s) = Showed that
a sealed flask of meat broth sterilized by
boiling failed to grow microbes
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 Rudolf Virchow – Biogenesis theory
The alternative hypothesis, that the
living organisms arise from
preexisting life, is called biogenesis
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Louis Pasteur (1861)


Microorganisms can be present in
air, liquid, and solids and “heating
will destroy them”
Basis for aseptic techniques,
sterilization, and pasteurization.
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Louis Pasteur (1860s) = Discovered the
microbial basis of fermentation
- Devised “swan neck” flasks
Figure 1.14
- Showed that,
after boiling, the
contents remain
free of microbial
growth despite
access to air
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Germ Theory of Disease
Figure
1.15
Robert Koch (1843–1910)
- Founder of the
scientific method of
microbiology
- Developed
pure-culture techniques
- Petri dish
- Agar
Figure
1.16
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Figure 1.17
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Immunization Prevents Disease
In the 18th century, smallpox infected a large
fraction of the European population.
Lady Mary Montagu introduced the practice
of smallpox inoculation to Europe in 1717.
Edward Jenner (1749–1823) deliberately
infected patients with matter from cowpox
lesions.
- The practice of cowpox inoculation was
called vaccination (Latin vacca for “cow”).
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Figure 1.18
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Louis Pasteur (1822–1895) developed the
first vaccines based on attenuated
(weakened) strains.
Figure 1.19
- Fowl cholera
- Rabies
Immunization = The
stimulation of an immune
response by deliberate
inoculation with an
attenuated pathogen
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Antiseptics
In 1847, Ignaz Semmelweis ordered doctors
to wash their hands with chlorine, an
antiseptic agent.
In 1865, Joseph Lister developed carbolic acid
to treat wounds and clean surgical
instruments.
In the 20th century, aseptic surgery was
developed.
- Environments completely microbe-free
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Antibiotics
In 1929, Alexander Fleming discovered that
Penicillium mold generated a substance that
kills bacteria.
In 1941, Howard Florey
and Ernst Chain
purified penicillin.
- The first commercial
antibiotic to save
human lives
Figure 1.20
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The Discovery of Viruses
Martinus Beijerinck = The agent of tobacco
mosaic disease is not a bacterium, because
it passes through a filter that retains bacteria
The filterable agent
was purified and
crystallized by
Wendell Stanley.
- Tobacco mosaic
virus (TMV)
Figure 1.21
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Microbial Ecology
Sergei Winogradsky (1856–1953) was among
the first to study bacterial in natural habitats.
- Discovered lithotrophs
- Developed enrichment
cultures
- Built the Winogradsky
column
- A wetland model
ecosystem
Figure 1.22
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Winogradsky and others showed importance
of bacteria in geochemical cycling.
Figure 1.23
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The Microbial Family Tree
Ernst Haeckel (1834–1919) = Microbes are
neither plant nor animal
- A third kind of life called Monera
Herbert Copeland (1902–1968) = Divided
Monera into two groups
- Eukaryotic protists (protozoa and algae)
- Prokaryotes
Robert Whittaker (1920–1980) = Added Fungi
as a fifth kingdom of eukaryotic microbes
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The Microbial Family Tree
The five-kingdom system was modified
dramatically by Lynn Margulis.
- She proposed that eukaryotic organelles,
such as mitochondria and chloroplasts,
evolved by endosymbiosis from prokaryotic
cells engulfed by proto-eukaryotes.
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Figure 1.26
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Figure 1.27
In 1977, Carl Woese was
studying recently discovered
prokaryotes in hot springs.
Analysis of the 16S rRNA
revealed that these
prokaryotes were a
distinct form of life.
- He called them
Archaea.
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Woese’s discovery
replaced the five
kingdoms with
the three domains:
Figure 1.28
- Bacteria
- Archaea
- Eukarya
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Advances in Cell Biology
Two instruments had exceptional impact on
the study of cell structure.
- The electron microscope
- Developed by Ernst Ruska
- Revealed internal structure of cells
- The ultracentrifuge
- Developed by Theodor Svedberg
- Enabled separation of subcellular parts
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Microbial Genetics
In 1928, Frederick Griffith discovered
transformation in bacteria.
In 1944, Oswald Avery et al. showed that the
transforming substance is DNA.
In 1953, Rosalind Franklin used X-ray
crystallography to determine that DNA is a
double helix.
Later that year, James Watson and Francis
Crick discovered the complementary bases
and antiparallel nature of DNA.
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Figure 1.31
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The DNA Revolution Began with Bacteria
The promise of DNA was first fulfilled in
bacteria and bacteriophages.
- Restriction endonucleases led to
recombinant DNA.
- A heat-stable DNA polymerase was used
for amplifying DNA via the polymerase
chain reaction (PCR).
- Gene regulation discovered in bacteria
provided models for animals and plants.
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Research in Microbiology
Research in microbiology finds applications in
diverse fields.
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Chapter Summary
● Most
microbes are microscopic and include
bacteria, archaea, fungi, algae, protists, and
viruses.
● Microbes have affected human civilization.
● Many scientists have contributed to our
understanding of microbiology. They include:
- van Leeuwenhoek = Observation of microbes
- Pasteur = Disproved spontaneous generation
- Koch = Developed the Four Postulates
- Jenner = Developed vaccination
- Fleming = Discovered antibiotics
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Chapter Summary
●
Microbes perform unique roles in
geochemical cycling.
●
The three domains of life are Bacteria,
Archaea, and Eukarya.
●
Advances in microscopy and biochemistry
revealed the structure and function of the
various cell components.
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