Introduction to General
Microbiology
Instructor: Laura Hunt, PhD
Time: TTHR 8-9:20am
Why is microbiology interesting?
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Microbes can be
harmful but are a
necessary part of
our lives
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CNN: “Superbug succeeds by blowing up
defender cells, scientists learn” Nov 2007
What you will get out of this
class:
A general introduction to basic concepts
and principles of microbiology
 There is a lot of material to cover but
thankfully it is interesting and applicable
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The Importance of Microorganisms

The emergence of
higher life forms
 Biogeochemical
cycling
 Huge diversity and
physiological
capacities
 Relationships with
higher organisms
What does microbiology refer to?
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Microbiology is the study of microorganisms,
which can be unicellular or cell-cluster
microscopic organisms
– This includes eukaryotes: fungi and protists AND
prokaryotes: bacteria and certain algae
– Viruses, though not strictly classed as living
organisms, are also studied.
– Microbiology is a broad term which includes many
branches including virology, mycology,
parasitology and others.
Microorganisms as cells
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Cell is fundamental unit
of life
Compartmentalized
Dynamic systems
Cells constantly
communicate and
exchange materials with
their environment
Cell Chemistry
and Key Structures
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Four main components (macromolecules):
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Proteins
Nucleic acids
Lipids
Polysaccharides
Key structures:
– Cytoplasmic membrane
– Cytoplasm
– Nucleus
Characteristics of Living Systems
Cells as Machines and
as Coding Devices
The First Cells: when/where did the
first cell come from a non cell??
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Your just a bag of
carbon, oxygen, and
hydrogen
The RNA world
– Naked RNA are agents
of catalysis and coding
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First self replicating
entity had at least two
properties:
– 1. Means of obtaining
energy
– 2. Form of heredity
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More in Ch 11
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Microorganisms and Their
Natural Environments
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Cells live in assemblages
called populations
Habitat: location in the
environment where
microbial population lives
Microbial communities:
– Where populations live and
interact with other
populations
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Study of microorganisms in
their natural habitat is
called microbial ecology
The Effect of Organisms on Each
Other and on Their Habitats
Populations interact in various ways that
can be both harmful and beneficial
 Interaction between populations and
with physical/chemical environment
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The Extent of Microbial Life
Reservoirs of essential nutrients for life
 Total carbon equals that of all plants on
earth
 Prokaryotes comprise the major portion
of the Earth’s total biomass: 5 X 1030
cells
 Most prokaryotes lie underground in
oceanic and terrestrial subsurfaces
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1.4 The Impact of Microorganisms
on Humans
Microorganisms as disease agents
 Agriculture
 Food
 Energy and the Environment
 The Future: biotech
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Important in C,N,S
cycle
 Convert elements to
a form that is readily
accessible to plants
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Negatives: Food
spoilage and food
borne diseases
– E.coli in spinach
Energy of the Future??
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Microbial fuel cells
– Geobacter sp. are of interest
because of their novel electron
transfer capabilities
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Obtain energy from iron
oxides
Can transfer electrons to the
surface of electrodes
Use “nanowires” to shunt
electrons produced during
metabolic reactions onto the
surface of mineral grains in
the soil, to be taken up by
metal ions
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“The role of the infinitely small
in nature is infinitely large” -Louis Pasteur
The birth of microbiology:
Pathways of discovery
Slow to develop
 Two events:
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– Invention of the microscope
– Spontaneous generation controversy
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The Historical Roots of Microbiology:
Hooke, van Leeuwenhoek, and Cohn
Early Microscopy

Microscopes were crude,
and lacked resolution even
though they were
compounding.
 Some descriptions of
bacteria, but very poorly
seen
 Yet, considering the tools
many discoveries were
made
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Robert Hooke
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Described fruiting
structures of molds
in 1665
 First person to
describe
microorganisms
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Antoni van Leeuwenhoek
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Dutch draper and
amateur microscope
builder
 Contemporary of
Robert Hooke
 First person to
observe bacteria in
1676
 “wee animalcules”
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Slow growth
After initial discovery of tiny organisms,
the field was slow to develop for the
next 150 yrs.
 Two things became focus as the field
moved from the mid to late 19th century
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– Spontaneous generation
– Nature of infectious diseases
Ferdinand Cohn (1828-1898):
Science of Bacteriology
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Contemporary of Koch
and Pastuer
A botanist by trade
Discovered endospores
Laid groundwork for
bacterial classification
Sterilization techniques
Founded a major
scientific journal
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Cohn cont.
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Identified sulfur
bacterium Beggiatoa
mirabilis
Became interested in
heat resistant bacterium
– Led him to discover
Bacillus genus
– Described entire life
cycle
– (vegetative cellendospore-vegetative
cell)
– Heat did not kill the
endospore
Louis Pasteur (1822-1895)
French
microbiologist and
chemist
 Multi-faceted
career
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Pasteur and the Downfall of Spontaneous
Generation
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Ancient belief that
organisms arise from
nonliving materials
Louis Pasteur was a
major opponent to
spontaneous generation
Pasteur showed that
microorganisms present
in air resembled those
on putrefying materials
Showed that if you
sterilized you would not
have purification
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Pasteur’s Experiment
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In 1864, he crushed spontaneous generation
 Pasteur used a swan necked flask for his
experiment, now called a Pasteur flask
 Simple experiment ended the controversy
Pasteur and Vaccination
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Discovered that
attenuated strains
would provide
protection against
disease
– Made discovery with
chickens and cholera
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Helped solidify the
concept of germ
theory of disease
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Pasteur and Rabies Vaccine
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Known as the man who
invented the rabies
vaccine
“Benefactor of
Humanity”
First exp were on dogs
Then, July 6, 1885 tried
vaccine on Joesph
Miester, a boy bitten by
a rabid dog
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Pasteur Institute: 120yrs of
discoveries
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Diptheria
Plague
Immunology
Tuberculosis
Sulfamides
Molecular biology
AIDS
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Pasteur’s main contributions
Instituting changes in hospital/medical
practices to minimize the spread of
disease by microbes or germs
 Coined the term “vaccine” --from the
Latin vacca, meaning “cow”
 Weak forms of disease could be used as
an immunization against stronger forms
 Rabies was transmitted by viruses too
small to be seen under the microscopes
of the time, introducing the medical
world to the concept of viruses.
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Robert Koch and the Germ Theory of
Disease:
The Development of Koch’s Postulates
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Major contributions:
– Discovered anthrax
– Discovered the bacterium
that causes tuberculosis
and chlorea
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Koch’s postulates
– Developed based on
experiments with anthrax
in mice
– He took experiment one
step further and showed
that even after many
transfers in culture, the
bacteria could still cause
disease
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1.2 Koch’s Postulates
Koch’s Postulate and Coral Disease
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Corals are declining at
an alarming rate
30% worldwide decline
in corals
Satisfying Koch’s
Postulate to determine
the causative agent in
coral disease is
challenging and very
controversial
Coral Disease
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Hard to duplicate the
reef
Many diseases have
been described solely
on the basis of field
characteristics, and in
some instances there is
disagreement as to
whether an observed
coral condition is
actually a disease.
A disease pathogen has
been identified for only
handful coral diseases
The etiology of white pox, a lethal disease of the
Caribbean elkhorn coral, Acropora palmata Kathryn L.
Patterson* , James W. Porter�, Kim B. Ritchie､ｦ,
Shawn W. PolsonDeborah L. Santavy珥, and Garriet
W. Smith､PNAS 2002
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A Test of Koch’s Postulates:
Tuberculosis
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Discovered that the causative
agent of tuberculosis was
Mycobacterium tuberculosis
Considered his greatest
accomplishment
Used microscopy, staining, pure
culture isolation, and animal
systems
Won Nobel prize in 1905 his
work on tuberculosis
Koch and Pure Cultures
Developed methods to isolate a specific
microorganism into pure culture
 He observed individual colonies on
potato slices represented pure cultures
 He later developed other media that
was more uniform and reproducible with
gelatin and later with agar

Microbial Diversity and the Rise
of General Microbiology
From 19th to 20th century, microbiology
grew and improved significantly
 Several subdisciplines arose leading to
an era of “molecular microbiology”
 Two giants helped with this transition:
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– Martinus Beijerinck
– Sergei Winogradsky
Martinus Beijerinck (1851-1931)
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Biggest achievement: developed
the enrichment culture technique
Microorganisms isolated in a
selective fashion
Aerobic nitrogen-fixing, sulfatereducing,sulfur-oxidizing, nitrogenfixing root nodule, Lactobacillus,
and green algae
Using selective filter techniques,
discovered that the infectious agent
in tobacco mosaic disease, was not
bacteria--described the first virus
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Sergei Winogradsky (1856-1953): the
Concept of Chemolithotrophy
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Interested in bacteria involved
in the cycling of nitrogen and
sulfur
Introduced the concept that
bacteria could be important
biogeochemical agents
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Sergei cont.
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From studies on sulfur-oxidizing
bacteria:
– Chemolithotrophy: the oxidation
of inorganic compounds linked to
energy conservation
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From studies on nitrogen fixing
bacteria, concluded that they
obtained their carbon from CO2
From studies, proposed these
organisms were autotrophs,
specifically chemoautotrophs
Also isolated the first nitrogenfixing bacteria
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The Modern Era of Microbiology
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Development of the Major Subdisciplines of
Applied Microbiology
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Medical microbiology
Immunology
Agricultural microbiology
Industrial microbiology
Aquatic microbiology
Marine microbiology
Microbial ecology
Basic Science Sub disciplines
in Microbiology
Microbial systematics
 Microbial physiology
 Cytology
 Microbial biochemistry
 Bacterial genetics
 Molecular biology
 Virology
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The Era of Molecular
Microbiology
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By 1970’s, experimental manipulation of
genetic material
– Restriction enzymes
– Biotechnology
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Genomics:comparative analysis of genes of
different organisms
– Nucleic acid sequencing
– Phylogenetic relationships
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Proteomics: the study of protein expression in
cells
New Frontiers
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350yrs of research!
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