Louis Pasteur By Jamie Mignot Friday, February 27, 2004
"Imagination should give wings to our thoughts, but we always need decisive experimental proof.” These are the famous words of Louis Pasteur who was one of the greatest scientists of the nineteenth century.
Born in France in 1822, Louis Pasteur became a scientific giant, laying the foundation for several branches of science.
Pasteur is known as the father of microbiology and immunology; surprisingly, however, he began his career by studying the shapes of organic crystals.
Pasteur worked with tartaric acid and racemic acid whose crystals can be found in fermenting wine. Although these were two different acids, the chemical composition of the two was identical, and Pasture was determined to find out how this was possible.
Upon intense inspection beneath his microscope, Pasteur examined both acids and noticed that although they were identical, their spatial arrangement was different. One was the mirror image of the other. It was this discovery that led to the science of stereochemistry.
Pasteur’s next study allowed him to solve the puzzle of alcoholic fermentation. He concluded and was able to prove that living cells, the yeast, were responsible for forming alcohol from sugar, and that contaminating microorganisms turned the fermentations sour.
Upon this breakthrough, Pasteur then set out to find some of the specific microorganisms responsible for normal and abnormal fermentations in such things as wine, beer, and vinegar.
Pasteur demonstrated that if these substances were heated to a moderately high temperature for a few minutes, this would kill the living microorganisms and thereby sterilize (pasteurize) the substances and prevent them from spoiling.
MULTIPLE CHOICE What two types of acids did Pasteur base his study of organic crystals? 1. Steric and Hydrofluoric acids 2. Tartaric and Steric acids 3. Tartaric and Racemic acids 4. Racemic and Oleic acids 5. Steric and Racemic acids
During Pasteur’s time, there was great controversy over the theory of “spontaneous generation”. Many people believed that things such as beetles, eels, maggots and microbes arise spontaneously from decomposing matter.
Spontaneous Generation Pasteur conducted a series of clever experiments that destroyed every argument supporting "spontaneous generation". It was through these experiments that Pasteur proved that all life comes from preexisting life.
The previous achievements of Louis Pasteur were immense, however, they do not compare to the greatest achievements of Pasteur's career which was the development of the germ theory of disease and the use of vaccines to prevent these diseases.
While working on the study of fermentation, Pasteur noticed that the contamination of such things as wine and beer was due to airborne yeast. Pasteur thought that maybe this is how certain microorganisms (diseases) could be spread.
Germ Theory of Disease Pasteur observed several hospitals and noticed that infection was spread by physicians and hospital attendants from sick to healthy patients.
Germ Theory of Disease Because of this observation and remarkable finding, the germ theory of disease came about. Now sanitation, hygiene, and cleanliness are much more important in our society!
GERM THEORY OF DISEASE Pasteur’s germ theory of disease stated that most infectious diseases are caused by micro-organisms. It was time for Pasteur to apply his research on the germ theory of disease.
ANTHRAX Pasteur had a particular interest in the disease anthrax. Anthrax is an infectious disease that affects cattle, sheep, and other livestock that can be transmitted to man.
During this time, anthrax was responsible for killing large populations of sheep in France, and this was detrimental to the economy.
Pasteur carefully studied anthrax and noticed that some cows developed the disease more severely than others. So he decided to inject two cows with a strong dose of the anthrax bacteria, fully expecting them to die. Did they die?
To Pasteur's amazement neither of the cows developed the disease. Later, he found that both animals had already suffered from anthrax. Pasteur asked himself some questions. Could they be immune to it? Could they be protected in some other way? What do YOU think?
ANTHRAX Pasteur supposed that if it were possible to give an animal a mild attack, this might be sufficient to prevent the animal from getting the disease later on.
Pasteur’s hypothesis was correct. He eventually succeeded in producing a mild, weakened, harmless culture of anthrax bacteria. He then took this culture and vaccinated hundreds of livestock, and they were then immune to the disease. Click on the speaker to hear a sound clip about Pasteur’s discovery!
RABIES Pasteur is predominantly well-known for his work with rabies also known as hydrophobia. Rabies is a highly contagious, infectious disease that attacks the central nervous system. This disease is commonly looked upon with horror. When you hear of the disease rabies, what do you think of?
RABIES Many people have the misconception that those who have rabies act like a wild dog, barking and howling. Rabies enters the body through the bite of an infected animal or infected saliva.
RABIES Pasteur experimented with the infected saliva of rabid dogs and came to the conclusion that it did indeed affect the central nervous system. By studying the tissue of infected animals, Pasteur was able to produce diluted form of the virus. Would this vaccine work?
On July 6 1885, Pasteur tested his new rabies vaccine on man for the first time. Joseph Meister was a young man who had been bitten by a rabid dog. Urged to treat him with his new method, Pasteur gave Meister the rabies vaccine and saved his life.
Rabies was the last achievement for the astonishing scientist. Louis Pasteur could be deemed one of the greatest benefactors of humanity due to his numerous contributions. Click here to see a short movie clip on how the flu vaccine is created
True or False Louis Pasteur developed several vaccines for many infectious diseases. TrueFalse
Pasteur was responsible for some of the most important theoretical concepts and practical applications of modern science that we see and still use today.
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Acknowledgements • All clipart in this show is compliments of Microsoft. • The movie and sound clip were compliments of altavista. • Information from www.louisville.edu/library/ekstrom/special/pasteur/cohn.html