Louis PasteurBy

Dhairya Nagpal

"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.

Pasteur’s discoveries

were still not complete!!!

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.

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.

Spontaneous Generation

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.

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

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 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.

ANTHRAX

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.

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.

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

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.

Pasteur was responsible for some of the most important theoretical

concepts and practical applications of modern science that we see and

still use today.

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/spe

cial/pasteur/cohn.html

Presented by:

DHAIRYA

Presented to:

SCIENCE CLUB MEMBERS AND

RESPECTED TEACHERS

DHAIRYA NAGPAL