A Search For Better Health
Topic 4: Pasteur and Koch
Biology in Focus, HSC Course
Glenda Childrawi, Margaret Robson and Stephanie Hollis
DOT Point(s)
 describe the contribution of Pasteur and Koch to our
understanding of infectious diseases
world.edu
Introduction
In the second half of the nineteenth century there was a revolution
in microbiology, primarily due to the research of Louis Pasteur and
Robert Koch. Working separately, they were able to make an
invaluable contribution to our understanding of infectious disease.
en.wikipedia.org
www.nobelprize.org
Introduction
Although they each used aspects of the other’s work in their own
research, the degree of collaboration and communication was
minimal as they did not get on with each other.
www.br.de
Introduction
Prior to the work of Pasteur,
Koch and others, the
explanation for the cause of
disease and decay was the theory
of spontaneous generation. This
involved the idea that life, such
as the maggots that were present
in rotting flesh, arose
spontaneously from nonliving
things.
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Introduction
Pasteur was able to disprove this
theory and establish the ‘germ
theory of disease’. This theory
states that germs (microbes)
cause disease and that all microorganisms come from preexisting microorganisms.
mydailycomplaint.com
Louis Pasteur
Louis Pasteur (1822–1895)
was born in France, studied
chemistry and received many
awards for his work relating
crystal structure to optical
activity. Although not his
original area of study, he was
credited with creating the
science of microbiology and
made invaluable contributions to
the understanding of infectious
disease.
www.biography.com
Louis Pasteur
 Pasteur studied fermentation
of beet juice and found that the
process was due to the
presence of living organisms,
microbes called yeasts.
He also found that other microorganisms were responsible for
the souring of the alcohol
produced.
fx.damasgate.com
Louis Pasteur
Pasteur was instrumental in
finding that micro-organisms
(bacteria) were the cause of
wine, beer and vinegar spoilage.
He discovered that the solution
to the wine and vinegar problem
was to heat these solutions long
enough to kill the contaminating
bacteria that were present after
fermentation.
www.yourdictionary.com
Louis Pasteur
This was the beginning of the widely used process of
pasteurisation, still used today to ensure products such as milk are
free of disease-causing micro-organisms and are suitable to drink.
This process was initially used in milk production to destroy the
tuberculosis bacterium.
biologyblockb.blogspot.com
Louis Pasteur
Pasteur also found that the
rotting of foodstuffs was due to
the activity of living organisms.
 After further investigation he
entered into the debate about
spontaneous generation,
refuting this theory and
proposing the germ theory
of disease.
He carried out his famous ‘swannecked flask’ experiments to
gain evidence to support his
theory.
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Louis Pasteur
These experiments involved using
flasks that had long-drawn-out
necks (like those of swans) that
were not sealed. Meat broth was
boiled in the flasks and as they
cooled the air was drawn in from
outside. Any microorganisms
present in the air did not reach
the broth as they were trapped in
the narrow neck and the curve of
the glass.
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Louis Pasteur
No bacterial or fungal growth
was observed in these flasks.
Bacterial growth occurred if the
curve of the flask was broken off
and the contents of the flask
exposed to the air. Furthermore,
the tipping of a flask to allow the
solution in it to reach the curve
where the micro-organisms
were trapped resulted in
bacterial growth occurring.
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Louis Pasteur
This added further evidence to discredit the theory of spontaneous
generation. It proved that the organisms that contaminated the
broth and caused it to decay must be carried in the air and not be
spontaneously generated.
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Louis Pasteur
Pasteur’s flasks are on display at the Pasteur Institute in Paris and,
after nearly 150 years, the broth in the swannecked flask is still free
of bacterial growth. This classic experiment carried out by Pasteur
demonstrates how theories in science can be disproved.
adrianneabroad2012.blogspot.com
Louis Pasteur
 Pasteur also uncovered the relationship between microorganisms
and disease, and as specific bacteria became associated with
specific diseases, the spontaneous generation theory became less
widely supported and the germ theory of disease was more
widely accepted.
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Louis Pasteur
Pasteur investigated the cause of
anthrax and, after input from the
experiments of Koch,
determined that the animals that
were contracting the disease,
even though they had no known
contact with animals suffering
from the disease, did so due to
spores from the carcasses of
animals that died from the
disease. These carcasses had been
buried in the fields that were
grazed by healthy animals.
alphaonline1.com
Louis Pasteur
Pasteur, in the course of his
studies of fowl cholera, also
developed a way to attenuate, or
weaken, bacteria so that when
they are introduced into a host
they could cause the body to be
ready to recognise the real
infection. He had produced a
vaccine that prevented chickens
from developing chicken cholera.
partnersah.vet.cornell.edu
Louis Pasteur
He extended this work and
developed a vaccine for
anthrax. His detractors were not
convinced about the
effectiveness of the vaccine and
he was challenged to carry out a
public field test. This trial was
successful as all animals that
were given the vaccine before
being exposed to anthrax
survived, and the animals that
were not given the vaccine died.
ourenvironment.berkeley.edu
Louis Pasteur
The vaccine was found to be effective
and its use was widely adopted.
 He went on to develop vaccines for
a number of other diseases such as
rabies where he used the vaccine on
humans for the first time. Pasteur
had established the principle of
immunity and provided an effective
way to prevent infectious disease.
vaccineresistancemovement.org
Robert Koch
Robert Koch (1843–1910) was
born in Germany and obtained his
medical degree from Göttingen.
 he made innumerable
contributions to the field of
microbiology and the
understanding of infectious
disease.
He was an expert on bacteriological
techniques and many of the
techniques used today are based on
Koch’s original techniques.
en.wikipedia.org
Robert Koch
 He developed the agar plate
technique for growing
microorganisms that is still in
use today, and used it to
culture the isolated anthrax
bacillus.
general-anaesthesia.com
Robert Koch
Koch also carried out an
extensive study of the anthrax
bacillus. He examined the blood
of sheep that had died from
anthrax and identified rodshaped bacteria that he isolated
and grew in cultures. These
cultured bacteria were then
injected into healthy sheep that
subsequently developed anthrax.
www.nap.edu
Robert Koch
He repeatedly showed that the
anthrax spores he had obtained
from the pure cultures he had
grown could cause the disease in
other animals and kill them.
These experiments added further
weight to the germ theory of
disease as they showed that a
microorganism grown outside
the body caused a disease.
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Robert Koch
 Koch determined that each
disease is caused by a specific
microorganism. The principles
he used to identify the specific
micro-organism that was
responsible for a disease came
to be known as Koch’s
postulates and are still in use
today to identify the specific
micro-organism that causes a
particular disease.
fungalscience.blogspot.com
Koch’s Postulates
The steps that must be followed to determine if a particular microorganism is responsible for causing a disease are known as Koch’s
postulates and are given below:
1. The same micro-organism must be present in every diseased
host.
2. The micro-organism must be isolated and cultured in the
laboratory and accurately described and recorded.
3. When a sample of the pure culture is inoculated into a healthy
host, this host must develop the same symptoms as the original
host.
4. The micro-organism must be able to be isolated from the second
host and cultured and identifi ed as thewww.setyoufreenews.com
same as the original
species.
Robert Koch
One of Koch’s subsequent big breakthroughs was the discovery of
the bacterium responsible for tuberculosis, Mycobacterium
tuberculosis. He was also responsible for identifying the bacteria
responsible for causing cholera. He travelled extensively in the
latter part of his career to study diseases such as the bubonic plague
and African sleeping sickness.
bioultra.com
Homework
-Students to complete Contributions of Pasteur and Koch
worksheet