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A Great French Scientist's Contribution to the World of Science
Angel Miglani
(Year 9, OLSH College)

The Bio-Riddle

I was born on the 27th December 1822 in Dole. I found school to be boring, and I was not exceptionally bright. It was my father’s ambition for me to become a professor; however, I only delighted in drawing and fishing. It was not until secondary school that my talent in science lifted within my soul and I won a scholarship to the most prestigious French university. Studying crystallography and later fermentation, I began to be known to the world. I saved the world from small pox, anthrax, and cholera. Though many ridiculed me for my discoveries, I believed in myself and found a cure for rabies, as well. Being the discoverer of microbes and inventing the application of weakened microbes, I paved the way to the development of immunization. I passed away at the age of 72 on the 28th September 1895 and was named the ‘Great French Scientist’ (Le grand Scientifique français) . I also came up with the heating method to kill microbes in food without destroying the food. This method was named in my honour and called Pasteurization. My first name begins with L. Who am I?

Louis Pasteur
(1822-1895)

Louis Pasteur’s Contributions to the World of Science

The Great French Scientist, Louis Pasteur, devoted his life to solving problems of science, agriculture, medicine and the growing industry. His discoveries and cures have saved countless lives and have created new wealth for the world, not to mention the process of Pasteurization, vaccines for chicken cholera, rabies, anthrax and ways of preventing silkworm diseases. He was a very calm and precise worker. Once he was sure of his discovery, he would defend it strongly.

In 1847, at the age of 26, upon completion of his doctorate degree, Louis began to study crystallography. He did his first work on molecular asymmetry, bringing together the principles of Crystallography, Chemistry and Optics. He put together a fundamental law: “Asymmetry differentiates the organic world from the mineral world”. This meant that asymmetric molecules are always the product of life forces, i.e. spontaneous generation. His work became the basis of a new branch of science - Stereochemistry.

During his research on Optics, he found that a polarized beam of light that was passed through a pure solution made up of natural organic nutrients had its polarisation rotate either to the right or the left. Conversely, when such a beam was passed through a solution of artificially synthesized organic nutrients, there was no rotation of light’s polarisation. This result was puzzling because the presence of bacteria or other micro organisms again steered the beam of light’s polarisation to the right or left. Hence, Pasteur concluded that organic molecules are able to exist in two forms, namely isomers (having the same molecular identity but varying structurally) or stereoisomers, which refers to having the same structure but being the absolute mirror images of each other. These are also referred to as “Left handed” and “Right handed” forms, respectively. When an organic compound is synthesized, both forms are produced in equal proportions, and they cancel out each other’s optical effects. That explains why synthetic organic compounds did not seem to rotate the polarisation of light in Pasteur’s experiments.

In 1849, Pasteur moved to Lille, because he was appointed as Professor of Chemistry. There he began his research on Fermentation, which is defined as the chemical change in organic substances brought about by enzymes. Louis started off by examining the undesirable substances that so often contaminated alcohol during fermentation. Over time, he discovered that each sort of fermentation is actually linked to the presence of specific micro-organisms. He demonstrated that the fermentation that took place to yield alcohol was due to yeast as well as the presence of additional substances, such as bacteria. In addition, Louis also showed that bacteria can be eliminated by heating initial sugar solutions to high temperatures. Consequently, he was able to solve the problem of wine and beer turning sour, which had been a major economic concern in France.

Getting more intrigued with each passing moment by the developments, Pasteur extended these studies to other problems, such as the curdling of milk. He proposed a similar solution to counter the issue, which involved heating the milk to a high temperature and pressure before bottling. This method where milk is heated to 161 degrees Fahrenheit for 15 seconds, followed by a rapid cooling to 50 degrees Fahrenheit is currently known as Pasteurization. Pasteurization is a widely applied method as it removes unwanted bacteria from the milk, hence lengthening its shelf life.

In 1865, Pasteur had become the administrator and director of scientific studies at the Ecole Normale. He began studying silkworm diseases, which led to the discoveries of the infectious agents that were responsible for crippling the silk industry. He explained that these agents are transmitted through a hereditary principle, where the agent is passed on as the microorganisms reproduce.

Next in line was saving the world from smallpox, chicken cholera, rabies and anthrax. This great act was achieved based on his proven hypothesis that tiny microbes that are invisible to the naked eye, as well as to the microscopes of his time, were responsible for these diseases. Upon establishing the fact, Louis created vaccines by utilizing the actual disease-causing agents and weakening them to a certain degree such that they would not be able to cause the full-blown diseases. These vaccines function by directing the immune system; instigating the antibodies to go to war with the antigens. In the midst of this process, the immune system induces fever within the patient, as this will have an adverse effect on the heat-sensitive microbes. However, once all the antigens have been eradicated, the patient undergoes remarkable recovery. This was the genesis of immunization.

People who did not suffer from these diseases were strongly encouraged to get vaccinated. The vaccination exposed their bodies to a weakened strain of foreign antigens, enabling the immune system to develop pre-existing antibodies to the disease-causing agents in preparation for future infections. To date, vaccinations had saved millions of lives.

Quotes by Louis Pasteur -

�Do not put forward anything you can not prove by experimentation.�

�Chance favours only the prepared mind.�

�Let me tell you the secret that has led me to the goal. My only strength resides in my tenacity.�

�I am the most hesitating of men, the most fearful of committing myself when I lack evidence. But on the contrary, no consideration can keep me from defending what I hold as true when I can rely on solid scientific evidence.�

�Nothing is more agreeable to a man who has made science his career than to increase the number of discoveries, but his cup of joy is full when the result of his observations is put to immediate practical use.�

�To believe one has discovered an important scientific fact, to long to announce it, and yet to restrain oneself for days, weeks, sometimes even years; to strive to disapprove one�s own experiments; to publish one�s discovery only after exhausting every alternative possibility -yes the is a hard one. But when certainty is reached, the reward is one of the keenest joys of which the human soul is capable.�

�There is here no question of religion, philosophy, atheism, materialism, or spiritualism. I might even add they do not matter to me as a scientist. It is a question of fact; when I took it up, I was as ready to be convinced by experiments that spontaneous generation exists as I am now persuaded that those who believe it are blindfolded.�

�Young people, trust scientific method, whose first secrets we yet scarcely know. Don�t be discouraged. Live in the serene peace of laboratories and libraries. At the end of your life, you will be able to say: I have done what I could.�

What Louis Pasteur Meant to the Scientific Community

He did strange and impossible experiments, the kind that turn a crazy man into a genius when they come off. He tried to change the chemistry of living things by putting them between huge magnets. He devised weird clockworks that swung plants back and forward, hoping so to change the mysterious molecules that formed these plants into mirror images of themselves…

-Paul de Kruiff, from Microbe Hunters

“Pasteur was not a trained naturalist and he was working alone, without a tradition behind him and without associates with whom he could have shared his thoughts in moments of doubts or astonishment. The many brief notes which he left of his observations remind one of a child running hither and thither in a wood, dazzled by the manifestations of an unknown life which he half sees, half guesses, and delighted to discover the diversity of the Creation.”

-Professor Rene J. Dubos,
From Free Lance of Science

“He had to fight ignorance, prejudice, the innate conservatism of his eminent colleagues and of the medical establishment. He fought this fight, with kindness, good humour, and basic equanimity, which yet allowed the passion of his ‘exalted mind’ to drive him on and to inspire other …men with some of his own enthusiasm.”

-H.I., from Louis Pasteur and Microbiology

Note: This article was written by a Year 9 student from OLSH College, and is an encouragement for high school students to submit their work for publication.

References:

Beverly Birch, Louis Pasteur, 1990, Exley Publications, Great Britain.

http://www.louisville.edu/library/ekstrom/special/pasteur/cohn.html

http://www.lucidcafe.com/lucidcafe/library/95dec/pasteur.html

http://ambafrance-ca.org/HYPERLAB/PEOPLE/_pasteur.html

http://www.woodrow.org/teachers/chemistry/institutes/1992/Pasteur.html

http://www.accessexcellence.org/AB/BC/Louis_Pasteur.html

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