Download The Golden Age of Microbiology

Why Study Microbiology?
Infectious and parasitic diseases cause
more than 25% of annual deaths
worldwide (second leading cause of death).
- Lower respiratory infections
- HIV-AIDS
- Diarrheal diseases
- Malaria
- TB
- Measles
- Whooping cough
Why Study Microbiology?
Many diseases – some we thought were
under control – are re-emerging.
- Travel
- Global food market
- Anti-vaccine movement
- Homeless; crowding
- Multi-drug resistance
- Global climate change
- Inadequate health resources
Why Study Microbiology?
Microorganisms being linked to
diseases that were once not recognized
as infectious diseases.
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Example: Peptic Ulcers
As late as the 1980’s, experts believed
peptic ulcers were a result of lifestyle,
“smoking, drinking alcohol, stress, and
genetic predisposition.”
Causative agent: Helicobacter pylori
Microorganisms Beneficial
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Used in food
production
Source of antibiotics
Normal flora
Algae responsible
for 80% of earth’s
photosynthesis
Microorganisms Beneficial
Break down
organic matter
 Help plants grow –
nitrogen cycle
 Genetic
engineering hosts
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What Will We Study?
Bacteria
Yeasts
Molds
Immune response
Epidemiology
Viruses
Protozoans and
Helminths
Control of organisms
The Fields of Microbiology
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Table 1.3
MICROBIOLOGY
The study of organisms that are too small
to be seen with the unaided eye known
as microorganisms or microbes.
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Figure 1.18
Figure 1.7: Streptococcus within a human cheek cell
Prokaryotic
bacterial cells
Eukaryotic
cheek cell
LM
10 mm
FIRST OBSERVATIONS
1674, Antoni van
Leeuwenhoek
-Began making and using
simple microscopes
-Examined water and
visualized tiny animals, fungi,
algae, and single-celled
protozoa; “animalcules” –
-Now called microorganisms
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Figure 1.18
The Theory of Spontaneous Generation
• Some philosophers and scientists of the past
thought living things arose from three processes:
asexual reproduction, sexual reproduction, or from
nonliving matter
• Aristotle proposed spontaneous generation –
• “Living things can arise from nonliving matter.”
According to spontaneous generation, a “vital
force” forms life.
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The Golden Age of Microbiology
Many scientists began doubting Aristotle’s theory
and performed experiments to disprove the
theory of spontaneous generation
– Redi –
– decaying meat isolated from flies never developed
maggots
– Needham– Believed animals could not reproduce
spontaneously, but microbes could
– Spallanzani– Proved microbes exist in air and can contaminate
experiments
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The Golden Age of Microbiology
• Louis Pasteur’s “Swan neck Flask”
Experiment
– disproved Spontaneous Generation theory
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The Golden Age of Microbiology
• Debate over spontaneous generation was linked to
the question:
• What Causes Fermentation?
– Spoiled wine threatened livelihood of vintners
– Some believed air caused fermentation; others
insisted living organisms caused fermentation
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The Golden Age of Microbiology
Pasteur showed that microbes are responsible
for fermentation.
– Fermentation is the conversion of sugar
–to alcohol (to make beer and wine)
–or to acids (ie.lactic acid, acetic acid)
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Pasteurization
 Bacteria ferment sugar and
produce acetic acid, thus
spoiling wine by turning it to
vinegar (acetic acid).
 Pasteur demonstrated these
spoilage bacteria could be
killed by heat that was not hot
enough to evaporate the
alcohol in wine.
 This is called pasteurization.
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Figure 1.4
The Golden Age of Microbiology
What Causes Disease?
– Pasteur developed the germ theory of
disease
– Microbes cause disease, not “evil spirits”
“bad air” or “punishments from the
gods”
– Pathogen – specific germ that causes
disease (infectious agent)
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The Golden Age of Microbiology (Continued)
• Robert Koch
(1843-1910)
• Theorized that a “specific
microbe causes a
specific disease”
• Developed experimental
steps to prove that Bacillus
anthracis causes anthrax
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Koch’s Postulates
1. The causative agent
must be seen in case of
every disease.
2. The causative agent
must be isolated in pure
culture.
3. Inoculating the pure
culture into healthy,
susceptible animal must
produce the same
disease.
4. The causative agent
must be recovered from
the inoculated animal.
Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings
The Golden Age of Microbiology
• Koch’s Other Contributions
– Simple staining techniques
– First photomicrograph of bacteria
– First photomicrograph of bacteria in diseased
tissue
– Techniques for estimating CFU/ml
– Use of steam to sterilize media
– Use of Petri dishes
– Techniques to transfer bacteria
– Bacteria as distinct species
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Bacterial colonies on agar
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Figure 1.16
The Golden Age of Microbiology
• How Can We Prevent Infection and Disease?
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Semmelweis and handwashing
Lister’s antiseptic technique
Nightingale and nursing
Snow – infection control and epidemiology
Jenner’s vaccine – field of immunology
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The Golden Age of Microbiology (Continued)
How can we prevent infection and disease?
Ignaz Semmelweis advocated handwashing
to prevent transmission of puerperal fever
(childbed fever) in OB patients
 http://www.npr.org/blogs/health/2015/01/12/375663920/the-doctor-who-championed-hand-washingand-saved-women-s-lives
Joseph Lister used a chemical disinfectant
and aseptic technique to prevent surgical
wound infections after seeing Pasteur’s work
showing microbes are in the air
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The Golden Age of Microbiology (Continued)
Florence Nightingale introduced
antisepsis and aseptic technique
into nursing practices
John Snow– was a pioneer in
public hygiene, infection control
and epidemiology during a cholera
outbreak
Edward Jenner developed
vaccinations by inoculating a
person with cowpox virus in hopes
it would then protect him from
smallpox. The protection is called
immunity
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The Golden Age of Microbiology (Continued)
• How do we treat infectious
diseases?
Paul Ehrlich’s “magic
bullets” – field of chemotherapy
Alexander Fleming
discovered the first antibiotic
from observing the mold
Penicillium killed Staphylococcus.
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The Golden Age of Microbiology
• Discovery of viruses
Dmitri Ivanovsky , Russian botanist (1892)
– suggested a plant infection might be caused by a filterable toxin
produced by bacteria
Martinus Beijerinck , Dutch microbiologist (1898)
– convinced that the filtered solution contained a new form of infectious
agent, which he named virus meaning poison
• By the end of the 19th century, viruses were defined in terms of their
infectivity, their ability to be filtered, and their requirement for living hosts.
• The first images of viruses were obtained upon the invention of electron
microscopy in 1931
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The Modern Age of Microbiology
• Microbial Genetics
Genomics- the study of an organism’s genes
• Eduard Buchner (1897)
– Discovered enzymes catalyzed fermentation
• Beadle and Tatum (1942)
- Enzymes (proteins) are encoded in genes
• Avery, MacLeod, and McCarty (1944)
- DNA is the hereditary material -not protein
• Jacob and Monod (1961)
- Discovered the role of mRNA in protein synthesis
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The Modern Age of Microbiology
Genome Sequencingthe study of the order of genes in a genome
Pauling (1965)
 Provided understanding of evolutionary
relationships and processes
Carl Woese (1970’s)
 Discovered three cell groups (instead of two)
 bacteria, archaea, eukaryotes
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The Modern Age of Microbiology
 Genetic engineering
– Manipulate genes in microbes, plants, and
animals for practical applications
– Paul Berg (1960s)
– Studied recombinant DNA technology
DNA from two or more sources is incorporated into a
single recombinant molecule
– Gene therapy
– Inserting a missing gene or repairing a defective one in
humans by inserting desired gene into host cells
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The Modern Age of Microbiology
• What Role Do Microbes Play
in the Environment?
– Microbial Ecologythe study of
interrelationships
between organisms and
their environment
– Bioremediation uses living
bacteria, fungi, and algae to
detoxify polluted
environments
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Bioremediation
Spraying bacteria or fertilizer on spill
Clean rocks
Oil spill
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Scientific disciplines and applications
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Figure 1.19
The Future of Microbiology
The more questions we answer, the more
questions we have”
• Why can’t we grow some microbes in the lab?
• What can we learn from microbial communities
• What microbial genes cause pathogenicity
• How do we defend against microbes at the genetic
level
• How do we reduce threat of new and re-emerging
infectious diseases?
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