Transcript Spontaneous generation

Types of Microorganisms
Figure 1.1
The Debate over Spontaneous Generation
• Spontaneous generation: The hypothesis that
living organisms arise from nonliving matter; a
“vital force” forms life
• Biogenesis: The hypothesis that the living
organisms arise from preexisting life
• 1861: Louis Pasteur demonstrated that
microorganisms are present in the air
Conditions
Results
Nutrient broth placed in
flask, heated, not sealed
Microbial growth
Nutrient broth placed in
flask, heated, then sealed
No microbial growth
Spontaneous generation or biogenesis?
Figure 1.3
The Golden Age of Microbiology
• 1857–1914
• Beginning with Pasteur’s work, discoveries
included the relationship between microbes
and disease, immunity, and antimicrobial
drugs
Fermentation and Pasteurization
• Pasteur showed that microbes are responsible
for fermentation
• Fermentation is the conversion 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)
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
• Pasteurization is the
application of a high heat
for a short time
Figure 1.4
The Germ Theory of Disease
• 1876: Robert Koch proved
that a bacterium causes
anthrax and provided the
experimental steps,
Koch’s postulates, to
prove that a specific
microbe causes a specific
disease
Figure 1.4
Figure 14.3: Foundation Figure: Koch’s Postulates
1
Microorganisms are isolated
from a diseased or dead animal.
Slide 2
Figure 14.3: Foundation Figure: Koch’s Postulates
2a The microorganisms are
grown in pure culture.
Colony
1
Microorganisms are isolated
from a diseased or dead animal.
2b The microorganisms are identified.
Slide 3
Figure 14.3: Foundation Figure: Koch’s Postulates
Slide 4
2a The microorganisms are
grown in pure culture.
Colony
3
1
Microorganisms are isolated
from a diseased or dead animal.
2b The microorganisms are identified.
The microorganisms are injected into a healthy
laboratory animal.
Figure 14.3: Foundation Figure: Koch’s Postulates
Slide 5
2a The microorganisms are
grown in pure culture.
Colony
1
3
The microorganisms are injected into a healthy
laboratory animal.
4
The disease is reproduced in a laboratory animal;
microorganisms are isolated from this animal.
Microorganisms are isolated
from a diseased or dead animal.
2b The microorganisms are identified.
Figure 14.3: Foundation Figure: Koch’s Postulates
Slide 1
2a The microorganisms are
grown in pure culture.
Colony
1
3
The microorganisms are injected into a healthy
laboratory animal.
4
The disease is reproduced in a laboratory animal;
microorganisms are isolated from this animal.
Microorganisms are isolated
from a diseased or dead animal.
2b The microorganisms are identified.
5a The microorganisms
are grown in pure culture.
5b Identical microorganisms
are identified.
Figure 1.5
Figure 1.7
Figure 1.8
Ebola Hemorrhagic Fever
• Causes fever, hemorrhaging, and blood clotting
• First identified near Ebola River, Congo
• Outbreaks every few years
Figure 23.21