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Microbiology has had a long history and many individuals have made significant
contributions to the field
A few those important discoveries will be discussed in this video.
To begin we will discuss
the discovery of the microscope, exact origins at the microscope are debated
however there are three key individuals sacher as chanson
is the first to use inverted lenses
to make observations of his surroundings. More notably
is Robert Hooke an English scientist
make key observations of various organisms
including fungi. One of Hooke's most significant contributions
is he coined the term cell. Another notable scientist is Anton Van Leeuwenhoek.
Leeuwenhoek also made key observations
however he observed living microscopic organisms
which refer to as animalcules.
Leeuwenhoek is regarded as one of the first to provide accurate descriptions
of protozoa, fungi and bacteria
another key point
in history microbiology is the debate over the spontaneous generation
theory. The theory of spontaneous generation states that organisms
in this case microorganisms, arise from non-
living matter. However as science progressed
this theory became more and more disputed
One of the first to dispute the spontaneous generation
was Francisco Redi. In
sixteen hundred's Francisco Redi devised an experiment
in order to disprove that decaying meat gave way
to maggots. In order to disprove this theory
he placed decaying meat in the bottom of several jars,
some jars were left open as you can see here to the left
and other jars were sealed with the lid to prevent the entry
of the flies, as you can see here on the right.
The next day
Redi found the jars which
had access to flies had maggots
developed on the decaying meat, where as those in which the jars were sealed had
no maggots developed. Supporters of the spontaneous
generation theory disputed Redi's experiment claiming by sealing the
jars with lids
he prevented those vital forces needed for life. Therefore Redi revised his
experiment.
This time adding a third set of jars
in which he sealed them with netting similar to gauze.
The next day he came back and found that he had achieved very similar results
the jars which had open lids
and exposed to the flies had maggots on the decaying
meat, those with the sealed lid and those with the netting or gauze
did not have maggots on the meat. Thus he thought
disproving spontaneous generation. But even by the seventeen hundred's
the spontaneous generation debate was still in progress
although by this time scientists agree
larger animals, such as the flies, could not arise
from spontaneous generation. However
the debate was on the origin of the animalcules
as described by Leeuwenhoek. Obviously
those very small organisms had to arise
from spontaneous generation. An English man named John
Needham tried to advance the theory of spontaneous generation
to do so he boiled beef gravy and plant infusions
in flasks, boiling them to remove
all life forms. After he boiled them he left some jurors have been
and he sealed others with corks.
After several days
he found them both flask contained
cloudiness and microscopic
animals.
Lazzaro Spallanzani disputed spontaneous generation
and Needham's experiment. He said
the broth was not properly boiled
or sealed and that was the reason that Needham
got growth in his broth.
Therefore Spallanzani redesigned
the experiment, he too boiled broth
in flask but instead of using corks
to seal his flask he heated the neck of the flask
hot enough in order to seal the glass together.
He found days later
that the sealed flask did not contain growth
nor did it contain microscopic animals.
Not until the flask or the seal was broken
did the broth get contaminated
Spallanzani concluded that the microorganism actually existed in the
air and when they were not seal properly
would contaminate the experiments, and the growth was a result
being contaminated.
Although this made significant
way for the spontaneous generation theory to be disproved
the debate lingered until the eighteen hundred's
and the work at Louis Pasteur. Louis Pasteur worked on numerous experiments
during this time
especially working with wine and the dairy industry to learn
why their products spoiled so
readily. He soon found that
bacteria were to blame
Due to his work with the wine and the dairy industry
pasteur begin to conclude it bacteria could spoil
milk and wine perhaps they were the cause
of human illness as well
In order for Pasteur to prove his theory he first had to disprove spontaneous
generation.
To do this he devised a new type of flask
as seen here known as the swan-neck
flask and as you can see the flask has
a S or curved shaped in it.
The curve in the neck prevents the microorganisms from the air
from falling into the broth as they're heavier and will collect
in that curvature. With his newly designed flask
Pasteur filled the flask with broth and heated the broth
to remove any pre-existing microorganisms that may be present
and then he left the flask open to the air.
after much time he found that the flask
did not become contaminated.
Thus proving that the microorganisms were actually
in the air and disproving once and for all
spontaneous generation.
Pasteur in all of his experiments
concluded that microorganisms
maybe the cause of infectious disease,
and therefore that got him to postulate what is known as the Germ
theory of disease.
As long as he tried Pasteur was still unable to prove
his own theory. However
German scientist Robert Koch did prove
the germ theory of disease. He was able to do so by isolating the causative
agent
for anthrax which he named Bacillus anthracis.
He was able to isolate the bacteria
through an established sequence of experimental steps.
These steps are known as Koch's postulates
and are still used today to associate
various microorganisms with diseases
As the understanding of microbes and their relationship to diseases grew,
it was important to learn more about disease transmission
itself. Epidemiology is the study at the source, cause, mode of transmission of
diseases. American scientist
Oliver Wendell Holmes was the first
to write about the spread of disease by healthcare workers.
In particular he wrote about
health care workers spreading childbirth
fever amongst its patients.
His work is what began field epidemiology.
Through the work of Holmes and Pasteur
new scientist such as Ignaz Semmelweis
was inspired, and implemented hand-washing practices
in the birthing ward in which he ran in order to
prevent attending health care workers from spreading diseases
amongst their patients. Joseph Lister
an English surgeon also applied
the germ theory of practice and started using phenol
to clean wounds and dressings up his patients.
Lister was the first to show microorganisms responsible for surgical
wound
infections.
The work up these three scientists and Pasteur
ultimately lead to aseptic techniques that we still used today
and were the reason that we were able to halt epidemics
as they were able to interrupt this spread of microorganisms
by implementing many up their techniques.
Despite the advances being made in microbiology
and the relationship between microbes and disease
it wasn't until the early nineteen hundred's
that there was actually methods developed to help
patients who were infected with these microbial diseases.
Two significant events in medical microbiology
need to be noted, first was in 1910 and the discovery
of salvarsan, which is an arsenic derivative
and Paul Ehrlich discovered salvarsan
and used it to help treat patients who had syphilis
The second is in 1928 when Alexander
Fleming discovered penicillin when working with the fungus
Penicillium notatum. This led to
development antibiotics.
Up until mid 1900s most of the discoveries
in microbiology were working on
the bacterium as work with the viruses could not be
effectively performed due to the lack of proper instrumentation.
However in the 1940s the electron microscope was developed
soon after cultivation methods for viruses were also introduced
With these two discoveries the knowledge on viruses developed
rapidly and is continuing to grow.
The field microbiology continues to grow and is now one of the fastest growing
divisions
in the biological sciences.