2 Lecture - Outline
Development of Microbiology
A. Discovery of microorganisms is dependent
on microscope.
B. Experimental science removed belief in
spontaneous generation.
C. Early observations relating microbes and
diseases.
D. The Golden Age of Microbiology.
Founders of Microbiology
Koch
Leeuwenhoek
Pasteur
Discovery of microorganisms is
dependent on microscope
Robert Hooke Curator of Experiments for the
Royal Society of London
1665 published Micrographia
Description of microscopes including the compound
microscope (It was first described at end of 16th Century)
Observational drawings 25X of cells and common bread
mold (First observation of a microoganism)
Antoni van Leeuwenhoek cloth merchant Holland
saw Hookes Micrographia
Became interested in microscopes
Became skilled in grinding single piece glass lens
microscopes - Simple microscopes
Leewenhoek Microscope.
Single lens
Magnification
around 300X to
500X
Antoni van Leeuwenhoek
Antoni van Leeuwenhoek communicated his
observation with Royal Society of London.
1674 - found wee animicules in pond water (probably
protozoa).
1684 bacterial cells from dental plaque
(first finding of bacteria)
The number of these animalcules in the
scurf of a mans teeth are so many, that
I believe they exceed the number of
men in a kingdom.
-- Antoni van Leeuwenhoek, 1684
The Transition Period
Leeuwenhoek time:
1. Belief animalcules arises spontaneous.
2. No correlation between disease and
microbes
B. Experimental science removed belief
in spontaneous generation.
Spontaneous generation
Basis of the doctrine
Redi's experiments
Needham's objections
Spallanzani's experiments
Pasteurs experiments
Spontaneous Generation
Spontaneous generation was belief
until early 18th century that life
arises spontaneously from non-living
matter.
Francesco Redis experiments
[1688]
Disproved that maggots arise from decaying meat.
Fig. 1.4
Spontaneous generation
(continued)
Fact: It was known that if an extracts of
meat broth was prepared and left at
room temperature, it soon became
cloudy from the growth of microbes.
Where did these microbes come from?
Two schools of thought:
a. Spontaneous generation
hypothesized decay of complex
organisms results in their molecules
reorganizing into animalcules
b. Formed from seeds or germs.
living cells arise only from other
living cells.
John Needhams
Experiment [1748]
John Needham was a British clergyman
and a vitalist .
Vitalist believed a vital force pervaded all
organisms.
Experiment boiled mutton gravy and
sealed the tubes with cork.
Result: Found microscopic animals
Proof Putrefaction could generate the vital
force needed for spontaneous generation
[ Was elected to Royal Society of London]
Lazzarro Spallanzani
experiment [1767]
Italian priest Lazzarro Spallanzani first
suggested:
life arise only from other living cells
He showed that heating a sealed flask of meat
broth resulted in no growth of organisms.
_________________________________________
However, skeptics (including Needham) claimed that:
Excess heating destroyed the vital force or
It was the lack of fresh air that prevented growth.
- Louis Pasteur
[ 1859]
French Academy of sciences sponsored
a contest for the best experiment to
prove or disprove spontaneous
generation.
Louis Pasteur
refuted the doctrine of spontaneous
generation.
1859 - Louis
Pasteur
disproved
spontaneous
generation
C. Early observations relating microbes
and diseases
Epidemiology is scientific study from
which the source, cause and mode of
transmission of a disease can be
identified.
1. Early epidemiology suggested how
diseases
could be spread
Direct human contact
Bad air miasma
could be controlled
quarantine
Observations relating microbes and
diseases continued
Mid - 1800
In 1847, Ignaz Semmelweis, a Hungarian physician,
working in Vienna noticed that blood poisoning was
transferred to maternity patients by physicians but was
low maternity patients of midwives.
Found hand washing and chlorine disinfections prevent
disease.
In 1854, John Snow performed first epidemiological
study of a cholera epidemic in London.
Interviewed sick and healthy Londoners
Plotted location of each cholera case
Found cluster around street pump from which local
residents obtained drinking water
Removed pump handle and disease spread was broken.
Snow proposed cholera was a waterborne disease.
Observations relating microbes and
diseases continued
Resistance comes from exposure to and
recovery from disease.
Smallpox epidemics were so severe that one third
children died before reaching three.
But survivors were protected from suffering the
disease a second time.
Variolation - is a method of purposefully
infecting a person with smallpox (Variola) in a
controlled manner so as to minimize the
severity of the infection and also to induce
immunity against further infection.
Chinese and Indians blew ground smallpox
powder into individuals nose.
Europeans put dried smallpox scab under skin.
Vaccination
Edward Jenner notices that people who got the
relatively mild disease called cowpox
(milkmaids) didnt get smallpox.
Tested 1796.
He scratch cowpox on skin of a boy who then had a
mild disease.
Then 6 week later scratch boy with smallpox. Boy
developed no reaction to smallpox
Jenners procedure vaccination [ vacca = cow ]
By 1801 over 100,000 people in England vaccinated.
Other who set the stage
for the "germ revolution
1830s - advanced on microscope optics.
1838 - German biologics - Christian
Erenberg suggested tiny "rod-like" looking
organisms be called bacteria.
bakterion = "little rod"
1840 - Swiss physician Jacob Henle
suggest living organisms can cause
disease.
1854- Filippo Pacini saw comma shaped
bacteria in the stool samples of cholera
patients.
C. The Golden Age of Microbiology
1854 - 1914
1. Louis Pasteur
The swan-neck flask experiment
disproved spontaneous generation
(1859).
Yeasts and fermentation (1857).
The germ theory of disease (1857).
Pasteur- Father of Microbiology
1857 - Louis Pasteur saves Frances
wine industry.
Napoleon III begged Pasteur (a chemist by
training) to help solve a problem - Sailors were mutinying because their
wine was spoiling after only a few
weeks at sea.
Pasteur armed with his trusty microscope
accepted the challenge.
1857 - Louis Pasteur saves
Frances wine
1) He observed that good wine contained
one kind of microbe, which we now know
to be yeast.
2) Sour wine contained a much smaller
microbe, which we know to be a
bacterium.
3) He then reasoned that if one heated the
wine to a point where its was
unaffected, flavor but the harmful microbes were
killed it wouldnt spoil. (process known as
Pasteurization).
Germ theory of disease
Pasteur proposed that wine spoiling
is an analogy for disease.
Bacterial growth made the wine sick.
He hypothesized in 1857 that
microorganisms are responsible for
infectious diseases.
The germ theory of disease
Louis Pasteur - Other discoveries
microbes can grow without oxygen
(anaerobic growth)
fermentation by yeast produced alcohol
microorganisms in beer and wine could be
killed by heat
milk pasteurization
different microbes caused different types of
fermentation
developed vaccines for diseases such as
rabies
Effects of Pasteurs Germ Theory
Father of modern antiseptics
1865 Joseph Lister- Professor of Surgery
Glasgow Scotland.
Fact: Near 50% of the amputation patients died
not from the surgery but from postoperative
infections.
Heard about Pasteurs germ theory.
Argued that surgical infections are from
living organisms in the air.
Found survival rate of his surgical
patients increased if
Used carbolic acid (phenol solution) spray in
surgery,wounds and on medical instruments.
2. Robert Koch
Pure culture techniques
Proved of the germ theory
Work with anthrax
Koch's postulates
Robert Koch (1843 - 1910)
German country physician who
developed microbiology into a
science.
Developed Pure culture techniques
Used Potato slices - first found individual
bacterial colonies growing with different
appearance.
microscopic examination revealed cells within
a single colony were similar (pure).
Pure Culture Key
To Studying Microbes
Definition: Pure culture is a
population of organisms, all of which
are the progeny of a single organism.
In nature, microbes almost never occur
as pure cultures.
Development of solidifying agents and
complex media
Koch wanted to culture pathogens so he
used something similar to the body tissue
- meat extracts.
Initially, Gelatin(Jell-O)- was used to
solidify beef extract broth.
But, (1) many organisms can digest
gelatin and
(2) it melts at 37 C, the favored
incubation temperature for most
pathogens.
Development of solidifying agents
Agar- was suggested by Fannie Hesse wife of
Walther Hesse working in Koch lab.
Story: Walther was working with gelatin plates
in summer and was having troubles.
Asked wife Why do your jellies and pudding
stay solid in warm weather?
Fannie learned to use AGAR-AGAR from a
Dutch neighbor in New York who spent time in
Asia.
AGAR-AGAR had been used as a gelling agent
in Asia for centuries.
Agar
Agar is complex polysaccharide derived
from seaweed
It only melts at 100 C, but solidifies at
about 45 C.
Non-toxic to most microbes and other
forms of life.
Stable at sterilization temperatures
Physiologically inert. (Only a very few
bacteria have enzymes that digest it. )
Petri Dish
Petri Dish was
invented in 1887
by an assistant of
Koch, R.J. Petri
They are shallow
glass plates.
Koch - Established Microbial
Taxonomy
Pure cultures of bacteria don't change
shape.
even after several transfers to new media
He realized there are many different
types(species) of bacteria.
1884 - Hans Christian Gram
A colleague of Koch developed the
Gram stain to distinguish between
different types of bacteria that look the
same.
Kochs Experiment
He showed with anthax, a disease of
cattle that:
a. Sick animals had the bacterium in their
blood, while healthy animals didn't.
b. Blood from sick animals could make
healthy animals ill.
Kochs Experiment continued
c. He was able to culture the bacterium
from a sick animal in nutrient media.
d. A pure culture of the bacteria when
injected into healthy animals
caused the disease, ( and it was not
something else in the blood).
Thus, the bacterium (Bacillus anthracis)
caused the disease
Kochs Experiment in Picture
Fig. 1.10
Koch's Postulates
[1] That a specific microorganism is
present in all cases of the disease.
present
[2] That the organism can be obtained in
[2]
pure culture outside of the host.
pure
[3] That the organisms, when inoculated
[3]
into a susceptible host, causes the
same disease symptoms.
same
[4] The organisms can be isolated in pure
[4]
culture from the experimentally infected
host.
host.
Using Koch's postulates
Koch and his coworkers discovered:
1882 - bacteria caused Tuberculosis
1884 - bacteria caused Cholera
1884 - bacteria caused Diphtheria
(Friederich Loeffler)
1884 - bacteria caused Typhoid fever
(Georg Gaffky)
1885 - bacteria caused Gonorrhea
1886 - bacteria caused Pneumonia
Competition Fueled the Study of
Infectious Diseases
Pasteurs lab studied
The mechanisms for infection
Developed vaccines for chicken cholera and
human rabies
Kochs lab focused on
Isolation, cultivation and identification of
pathogens
Tuberculosis
Typhoid fever
Diphtheria
The discovery of endospores
1877 - John Tyndall found
microorganisms in a hay infusion could
survive boiling.
1877 - Ferdinand Cohn demonstrated
heat resistant microbes were
"endospores.
Structure in favorable conditions
germinate and form new Bacillus cells.
Structure is made by bacteria (such as
Bacillus).
Filterable agents - Viruses
Ivanowsky (1892) and Beijerinick (1899)
provided the first evidence for viruses
as infectious agents.
Tobacco mosaic disease was a
contagious, living liquid can pass
through filters that traps bacterial cells.
It thus acted like a poison or virus
(virus = poison).
Other pioneers of microbiology
See Table 1.2 in book
Emile Roux and Alexandre Yersin
(France) Identified the diphtheria toxin.
Emil von Behring (Germany) Developed
the diphtheria antitoxin
Charles Nicolle (France)- Proved that lice
transmit typhus fever.
Masaki Ogata (Japan) Discovered that
rat fleas transmit plague.
Walter Reed (United States) Proved that
mosquitoes transmit yellow fever.
Modern Era begins with finding
Antimicrobial Agents
1910 - Paul Ehrlich introduced an
arsenic-containing chemical called
salvarsan to treat syphilis.
1928 - Alexander Fleming discovered
penicillin (first antibiotic).
1933 - Gerhard Domagk discovered sulfa
drugs.
Microbial Menagerie
Founders of Microbiology (Review)
First observed bacteria.
Leeuwenhoek
Proved living cells can arise only
from other living cells.
Pasteur
Confirmed the Germ Theory of
Disease.
Koch
Lecture 2 Objectives
Discuss origins of microbiology and how
they relate to studies on spontaneous
generation.
Describe the contribution of Louis
Pasteur and Robert Koch to the
development of the science of
Microbiology.
Germ theory of disease
Pure culture technique (& Agar)
Kochs Postulates