Chapter 1: Introduction to Microbiology
¡  Microbes
consist of a variety of
organisms:
Bacteria
l  Algae
l  Fungi
l  Viruses
l  Protozoa
l
¡  Less
than 1% of known
microorganisms cause disease
Types of Microbes
Cellular
Prokaryotes
Acellular
Eukaryotes
Viruses
(b) VirusTypes
(a) Cell Types
Prokaryotic
Eukaryotic
Chromosome
Nucleus Mitochondria
Ribosomes
Envelope
Capsid
Ribosomes
Nucleic
acid
AIDS virus
Cellwall Cell
membrane
Flagellum
Bacteria and
archaea
Flagellum
Cell membrane
Fungi,algae,
protozoa, helminths
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Bacterial virus
Viruses and
bacteriophages
Ebola Virus: zoonotic, unknown
reservoir
Reservoirs:
continual source of microbe (can be
nonliving)
Epidemiology
¡
¡
Animation
Study of disease and when/where it occurs
Evolutionary Time Line
Microbes in the Environment
¡
¡
¡
¡
Study of Environmental
Microbiology
Microbial
account for most of the
atmospheric oxygen on
Earth
Microbes are essential for
decomposition of dead
organisms
Many biologically important
elements (S, N, P) are
cycled by microbes
Human Use of Microorganisms
¡  Humans
have been using
microorganisms for
thousands of years
Baker’s and brewer’s yeast
l  Cheeses
l  Moldy bread on wounds
l
Harnessing the Power of Microbes
¡  Studies
of Industrial
Microbiology and
Food Microbiology
¡  Microbes can be
used to make or
preserve food
products (e.g. yogurt,
salami, cheeses)
¡  Microbes can
produce important
compounds (e.g.
antibiotics, MSG,
ethanol)
Biotechnology and Bioremediation
¡
¡
Biotechnology- when humans manipulate
microorganisms to make products in an industrial setting
l  Genetic engineering- create new products and
genetically modified organisms (GMOs)
l  Recombinant DNA technology- allows microbes to
be engineered to synthesize desirable proteins (i.e.
drugs, hormones, and enzymes)
Bioremediation- introducing microbes in to the
environment to restore stability or clean up toxic
pollutants
l  Oil spills
l  Chemical spills
l  Water and sewage treatment
Recap: Microbes can be good!!!
¡
Essential to life!
Photosynthesis
l  Nitrogen fixation
l  decomposers
l  Food, fermentation, sewage
l  Genetic engineering (fast reproduction,
cheap)
l  Boiremediation
l  Natural flora (10X our # of body cells),
microbial antagonism, bacteriocins.
l
Where are natural flora?
Normal Microbiota
a) Bacteria on skin
b) Dental Plaque
c)Large Intestine
Probiotics
¡  LAB
(lactic
acid bacteria),
can prevent
colonization
by pathogenic
bacteria.
Terms:
¡  Pathology:
study of disease
¡  Etiology: cause of disease
¡  Endemic: constantly present
¡  Epidemic: sudden spike in
prevalence
¡  Pandemic: Epidemic that occurs
world wide
¡  Herd Immunity
History of Microbiology
¡  Hooke
¡  Leeuwenhoek,
“animalcules”
¡  Spontaneous Generation (Redi,
Pasteur, Tyndall)…needed heat
destroyed organisms (no spores!!)
¡  Schleiden & Schwann (Cell Theory)
and biogenesis.
Pasteur’s other Contributions
¡  Wine
and silkworm industries
¡  Rabies vaccine
¡  Cholera immunization in chickens
using old cholera cultures
Robert Koch & The Germ Theory
(infectious disease caused by a single
organism, anthrax)
¡
¡
Able to grow bacteria in a pure culture
(using agar), colony = billions of identical
cells
Germ Theory
l
l
l
l
Causative agent found in every case of disease
Agent is isolated in pure culture
Inoculation of culture into healthy animals causes
same disease
Agent is recovered from inoculated animal
Koch’s Postulates
Proving the germ theory
¡
Reed did a variety of “questionable”
experiments to prove that yellow fever
was an infections agent from mosquitoes
l
l
l
¡
Volunteers allowed themselves to be bitten =
got sick, some died (including coworker,
Carroll)
Slept on filthy sheets from yellow fever
patients = didn’t get sick
Passed blood from sick to healthy
(paid)volunteers = 2 out 3 died Yellow fever =
filtered blood, still got sick
Yellow fever = virus, was able to pass
through a filter
Lister
¡  Used
carbolic acid on bandages and
during operations.
¡  Aseptic techniques, decrease in
wound infections
Jenner & smallpox vaccinations
¡  1800’s
inoculated own son with
cowpox blister from milkmaids.
Vacca (cow) = virus name and
vaccine
¡  Before this the only prevention for
smallpox = variolation (ground up
smallpox blister blown up nose)
Chemotherapy: Flemming
¡  Lysozyme
(in tears, saliva, sweat)
can kill bacteria
¡  Antibiotics (Penicillium mold
inhibited Staphylococcus), other
antibiotics made from bacteria in
soil and fungus found in ocean
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.
Figure 1.5
Microbes are EVERYWHERE
¡
HUGE variety!
l
l
¡
Subcrustal cultures
20nm à 5mm
(250,000X difference in
size)
Single gram of soil =
10,000 different types
of bacteria!
What are microbes? A closer look
¡  Microbes
consist of a variety of
organisms:
Bacteria/Archaea
l  Algae
l  Fungi
l  Viruses
l  Protozoa
l
Bacteria
¡  Prokaryotes
¡  Peptidoglycan
cell
walls
¡  Binary fission
animation
¡  For energy, use
organic chemicals,
inorganic
chemicals, or
photosynthesis
Figure 1.1a
Archaea
¡  Prokaryotic
cells
¡  Many are found in
extreme
environments
¡  Important nonpathogens
¡  Different from
Bacteria
Cell structure
Metabolism
Genetics
Fungi
¡  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
Figure 1.1b
Protozoa
¡  Eukaryotes
¡  Absorb
or ingest
organic chemicals
¡  May be motile via
pseudopods, cilia,
or flagella
Figure 1.1c
Algae
¡  Eukaryotes
¡  Cellulose
cell walls
¡  Use photosynthesis
for energy
¡  Produce molecular
oxygen and
organic
compounds
Figure 1.1d
Viruses
¡
¡
¡
¡
¡
¡
Acellular
Consist of DNA or RNA
core
Core is surrounded by a
protein coat
Coat may be enclosed
in a lipid envelope
Viruses are replicated
only when they are in a
living host cell
Very small, can pass
through porcelain filters
Figure 1.1e
Tobacco mosaic virus
the first to be
crystallized (Stanley)
Multicellular Animal Parasites
¡  Eukaryote
¡  Multicellular
animals
¡  Parasitic
flatworms and
round worms
are called
helminths.
¡  Microscopic
stages in life
cycles.
Figure 12.28
Taxonomy: Naming, Classifying, and
Identifying Microorganisms
Microbial nomenclature- naming
microorganisms
¡  Taxonomy- classifying living things
¡
l
Originated over 250 years ago with the work of Carl
von Linné
¡  Identification-
discovering and recording the
traits of organisms so they can be named and
classified
¡  Levels of Classification
Simple Taxonomy
Microbial Classification
¡  Taxonomy
is the science of living things
¡  Carl von Linné began systematically
classifying living things
¡  Every organism has a two-name
(binomial) designation – Genus species
¡  Note italics and the capitalization!
¡  What constitutes a species??
¡  Microorganisms push at the limits of our
ability to create schemes to organize and
classify them
Naming Examples
¡
¡
¡
Staphylococcus aureus
l  staphule-bunch of grapes
l  kokkus- berry
l  aureus - golden
Campylobacter jejuni
l  kampylos-curved
l  bakterion- little rod
l  jejunum- part of intestine
Giardia lamblia
l  Alfred Giard- Fr. Microbiologist
l  Victor Lambl – Bohemian physician
Levels of Classification
¡  Domain
¡  Kingdom
¡  Phylum
¡  Class
¡  Order
¡  Family
¡  Genus
¡  Species
or division
The Five Kingdom Model
Robert Whittaker
(1959)
1.
2.
3.
4.
5.
Animals
Plants
Fungi (microbes)
Protists
(microbes)
Monera
(microbes)
New Views of Phylogeny
Carl Woese
(1975)
¡  Used 16S rRNA
¡  Three “Domains”
¡
1.
2.
3.
Archaea
(all microbes)
Bacteria
(all microbes)
Eukarya
(some microbes)
Classification of Microorganisms
¡  Three
Domains
Bacteria
l  Archaea
l  Eukarya
l
¡  Protists
¡  Fungi
¡  Plants
¡  Animals
Microscopy: Ch 3
¡  It
is important to understand the relative
size of the organisms we are studying
¡  Generally, bacteria are measured in um
and can be seen with an oil immersion
light microscope
¡  Viruses are measured in nm and can
only be seen with an electron microscope
Principles of Microscopy
Ø
Ø
Microscopy is the technology of
making very small things visible to
the human eye
Table 3.1
1.  Milli = one thousandth 10-3 m
2.  Micro = one millionth 10-6 m
3.  Nano = one billionth 10-9 m
Scale animation
Properties of Light
¡  Light
travels as a wave and has the
properties of both a wave and a particle
¡  The shorter the wavelength of light, the
higher its frequency
¡  The higher the frequency of your light
source, the better resolution you can
obtain
The Electromagnetic Spectrum
¡  Only
a narrow range of wavelengths,
those of visible and ultraviolet light are
used in light microscopy
¡  The
shorter the wavelength used, the
greater the resolution that can be
attained
The
Electromagnetic
Spectrum
Resolution
¡  The
ability to distinguish two different
points as being separate
¡  DIFFERENT from magnification (simply
enlarging an image)…. Can be big, but
fuzzy
Resolution
Effect of
Wavelength on
Resolution
Effect of Wavelength on Resolution
¡
Many things can happen to light as it passes
through a specimen on a slide.
Reflection: If the light strikes an object and
bounces back (giving the object color)
l  Transmission: The passage of light through an
object
l  Absorption: The light rays neither pass through
nor bounce off an object but are taken up by the
object
l
¡
The more light that passes through the specimen
(vs. lost), the higher the resolution
Various Interactions of Light
Refraction
¡  The
bending of light as it passes from one
medium to another of different density
¡  The
bending of the light ray gives rise to
an angle of refraction, the degree of
bending
¡  Index
of refraction: A measure of the
speed at which light passes through the
material
¡  When
two substances have a different
index of refraction, the light is bent and is
scattered
¡  When two substances have a similar
index of refraction (diamonds and oil)
then the light is not bent as it passes
between the two substances
Refraction
Immersion Oil
Light Microscopy
Ø
Refers to the use of any kind of
microscope that uses visible light
to make specimens observable
2.
The compound light microscope
has more than one lens
Objective lens
Ocular lens
Ø
Monocular vs. Binocular
Ø
1.
The Compound Light Microscope
Electron Microscopy
Ø
Ø
Ø
Ø
1.
Uses a beam of electrons instead of a
beam of light
electromagnets rather than glass
lenses to focus the beam
Produce electron micrographs with
great detail
Two most common types of electron
microscopy:
Transmission electron microscopy
(TEM)
Electron Microscope
Cross-section
animation
Escherichia coli-Transmission
Electron
Microscopy
Escherichia coli-Scanning Electron
Microscopy
Aspergillus-Scanning
Electron
Microscopy
Radiolarian
(1761X)
Cyclotella
meneghiniana
(1584X)
Isolated Colonies
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Mixture of cells in sample
Parent
cells
Separation of
cells by spreading
or dilution on agar
medium
Microscopic view
Incubation
Growth increases the
number of cells.
Microbes become
visible as isolated
colonies containing
millions of cells.
Macroscopic view
Streak Plate Method
¡  Small
droplet of culture or sample spread
over surface of the medium with an
inoculating loop
¡  Isolated colonies are eventually obtained
Huge variety in Metabolism