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Louis Pasteur

2007 Schools Wikipedia Selection. Related subjects: Human Scientists

     French microbiologist and chemist
   Born December 27, 1822
        Dole, Jura, France
   Died September 28, 1895
        Saint-Cloud, Hauts-de-Seine, Dole

   Louis Pasteur ( December 27, 1822 – September 28, 1895) was a French
   microbiologist and chemist. He is best known for demonstrating how to
   prevent milk and wine from going sour, which came to be called
   pasteurization. His experiments confirmed the germ theory of disease,
   and he created the first vaccine for rabies. He became one of the main
   founders of bacteriology, the other major figure being Robert Koch. He
   also made many discoveries in the field of chemistry, most notably the
   asymmetry of crystals.

Biography

   Louis Jean Pasteur was born in Dole in the Jura region of France and
   grew up in the town of Arbois. His father, Jean Pasteur, was a tanner
   and a veteran of the Napoleonic wars. His aptitude was recognized by
   his college headmaster, who recommended that the young man apply for
   the École Normale Supérieure, which accepted him. After serving briefly
   as professor of physics at Dijon Lycee in 1848, he became professor of
   chemistry at Strasbourg University, where he met and courted Marie
   Laurent, daughter of the university's rector in 1849. Together they had
   five children, only two of whom survived to adulthood. Throughout his
   whole life, Louis Pasteur remained an ardent Catholic. A well-known
   quote illustrating this is attributed to him: "I have the faith of a
   Breton peasant and by the time I die I hope to have the faith of a
   Breton peasant's wife." ( Brittany is a rural region in France renowned
   for the Catholic piety of its inhabitants.)

Work on chirality and the polarization of light

   In Pasteur's early works as a chemist, he resolved a problem concerning
   the nature of tartaric acid ( 1849). A solution of this compound
   derived from living things (specifically, wine lees) rotated the plane
   of polarization of light passing through it. The mystery was that
   tartaric acid derived by chemical synthesis had no such effect, even
   though its reactions were identical and its elemental composition was
   the same.
   Pasteur's experiment proved paratartrate does not rotate polarized
   light while tartrate does.
   Enlarge
   Pasteur's experiment proved paratartrate does not rotate polarized
   light while tartrate does.

   Upon examination of the minuscule crystals of tartaric acid, Pasteur
   noticed that the crystals came in two asymmetric forms that were mirror
   images of one another. Tediously sorting the crystals by hand gave two
   forms of tartaric acid: solutions of one form rotated polarized light
   clockwise, while the other form rotated light counterclockwise. An
   equal mix of the two had no polarizing effect on light. Pasteur
   correctly deduced the tartaric acid molecule was asymmetric and could
   exist in two different forms that resemble one another as would left-
   and right-hand gloves, and that the organic form of the compound
   consisted purely of the one type. As the first demonstration of chiral
   molecules, it was quite an achievement, but Pasteur then went on to his
   more famous work in the field of biology/medicine.
   Pasteur separated the left and right crystal shapes from each other to
   form two piles of crystals: in solution one form rotated light to the
   left, the other to the right, while an equal mixture of the two forms
   cancelled each other's rotation. Hence, the mixture does not rotate
   polarized light.
   Enlarge
   Pasteur separated the left and right crystal shapes from each other to
   form two piles of crystals: in solution one form rotated light to the
   left, the other to the right, while an equal mixture of the two forms
   cancelled each other's rotation. Hence, the mixture does not rotate
   polarized light.

   Pasteur's doctoral thesis on crystallography garnered him a position of
   professor of chemistry at the Faculté (College) of Strasbourg.

   In 1854, he was named Dean of the new College of Science in Lille. In
   1856, he was made administrator and director of scientific studies of
   the École Normale Supérieure.

Germ theory

   Louis Pasteur demonstrated that the fermentation process is caused by
   the growth of microorganisms, and that the growth of microorganisms in
   nutrient broths is not due to spontaneous generation.
   Modified version of florence flask (Swan flask) made by Pasteur in his
   experiment for disproving spontaneous generation theory.
   Enlarge
   Modified version of florence flask (Swan flask) made by Pasteur in his
   experiment for disproving spontaneous generation theory.

   He exposed boiled broths to air in vessels that contained a filter to
   prevent all particles from passing through to the growth medium, and
   even in vessels with no filter at all, with air being admitted via a
   long tortuous tube that would not allow dust particles to pass. Nothing
   grew in the broths; therefore, the living organisms that grew in such
   broths came from outside, as spores on dust, rather than spontaneously
   generated within the broth. Thus, Pasteur dealt the death blow to the
   theory of spontaneous generation and supported germ theory.

   While Pasteur was not the first to propose germ theory ( Girolamo
   Fracastoro, Agostino Bassi, Friedrich Henle and others had suggested it
   earlier), he developed it and conducted experiments that clearly
   indicated its correctness and managed to convince most of Europe it was
   true. Today he is often regarded as the father of germ theory and
   bacteriology, together with Robert Koch.
   Louis Pasteur and his device for germ experiment.
   Enlarge
   Louis Pasteur and his device for germ experiment.

   Pasteur's research also showed that some microorganisms contaminated
   fermenting beverages. With this established, he invented a process in
   which liquids such as milk were heated to kill most bacteria and molds
   already present within them. He and Claude Bernard completed the first
   test on April 20, 1862. This process was soon afterwards known as
   pasteurization.

   Beverage contamination led Pasteur to conclude that microorganisms
   infected animals and humans as well. He proposed preventing the entry
   of microorganisms into the human body, leading Joseph Lister to develop
   antiseptic methods in surgery.

   In 1865, two parasitic diseases called pébrine and flacherie were
   killing great numbers of silkworms at Alès. Pasteur worked several
   years proving it was a microbe attacking silkworm eggs which caused the
   disease, and that eliminating this microbe within silkworm nurseries
   would eradicate the disease.

   Pasteur also discovered anaerobiosis, whereby some microorganisms can
   develop and live without air or oxygen.

Immunology and Vaccination

   Pasteur's later work on diseases included work on chicken cholera.
   During this work, a culture of the responsible bacteria had spoiled and
   failed to induce the disease in some chickens he was infecting with the
   disease. Upon reusing these healthy chickens, Pasteur discovered that
   he could not infect them, even with fresh bacteria; the weakened
   bacteria had caused the chickens to become immune to the disease, even
   though they had only caused mild symptoms.

   This discovery was serendipitous. His assistant Charles Chamberland (of
   french origin) had been instructed to inoculate the chickens after
   Pasteur went on holiday. Chamberland failed to do this, but instead
   went on holiday himself. On his return, the month old cultures made the
   chickens unwell, but instead of the infection being fatal, as usual,
   the chickens recovered completely. Chamberland assumed an error had
   been made, and wanted to discard the apparently faulty culture when
   Pasteur stopped him. Pasteur guessed the recovered animals now might be
   immune to the disease, as were the animals at Eure-et-Loir that had
   recovered from anthrax.

   In the 1870s, he applied this immunization method to anthrax, which
   affected cattle, and aroused interest in combating other diseases.
   Louis Pasteur in his laboratory, painting by A. Edelfeldt in 1885.
   Enlarge
   Louis Pasteur in his laboratory, painting by A. Edelfeldt in 1885.

   Pasteur publicly claimed he had made the anthrax vaccine by exposing
   the bacillus to oxygen. His laboratory notebooks, now in the
   Bibliotheque Nationale in Paris, in fact show Pasteur used the method
   of rival Jean-Joseph-Henri Toussaint, a Toulouse veterinary surgeon, to
   create the anthrax vaccine. This method used the oxidizing agent
   potassium dichromate. Pasteur's oxygen method did eventually produce a
   vaccine but only after he had been awarded a patent on the production
   of an anthrax vaccine.

   The notion of a weak form of a disease causing immunity to the virulent
   version was not new; this had been known for a long time for smallpox.
   Inoculation with smallpox was known to result in far less scarring, and
   greatly reduced mortality, in comparison to the naturally acquired
   disease. Edward Jenner had also discovered vaccination, using cowpox to
   give cross-immunity to smallpox (in 1796), and by Pasteur's time this
   had generally replaced the use of actual smallpox material in
   inoculation. The difference between smallpox vaccination and cholera
   and anthrax vaccination was that the weakened form of the latter two
   disease organisms had been generated artificially, and so a naturally
   weak form of the disease organism did not need to be found.

   This discovery revolutionized work in infectious diseases, and Pasteur
   gave these artificially weakened diseases the generic name of vaccines,
   to honour Jenner's discovery. Pasteur produced the first vaccine for
   rabies by growing the virus in rabbits, and then weakening it by drying
   the affected nerve tissue.

   The rabies vaccine was initially created by Emile Roux, a French doctor
   and a colleague of Pasteur who had been working with a killed vaccine
   produced by desiccating the spinal cords of infected rabbits. The
   vaccine had only been tested on eleven dogs before its first human
   trial.

   This vaccine was first used on 9-year old Joseph Meister, on July 6,
   1885, after the boy was badly mauled by a rabid dog. This was done at
   some personal risk for Pasteur, since he was not a licensed physician
   and could have faced prosecution for treating the boy. However, left
   without treatment, the boy faced almost certain death from rabies.
   After consulting with colleagues, Pasteur decided to go ahead with the
   treatment. Fortunately, the treatment proved to be a spectacular
   success, with Meister avoiding the disease; thus, Pasteur was hailed as
   a hero and the legal matter was not pursued. The treatment's success
   laid the foundations for the manufacture of many other vaccines. The
   first of the Pasteur Institutes was also built on the basis of this
   achievement.
   Louis Pasteur portrait in his later years.
   Enlarge
   Louis Pasteur portrait in his later years.

Honours and final days

   Pasteur won the Leeuwenhoek medal, microbiology's highest honour, in
   1895.

   He died in 1895, near Paris, from complications of a series of strokes
   that had started in 1868. He was buried in the Cathedral of Notre Dame,
   but his remains were soon placed in a crypt in the Institut Pasteur,
   Paris, and will be remembered for his life saving works.

Literature

Biographies

     * Debré, P.; Forster, E.: Louis Pasteur. Johns Hopkins University
       Press, 1998; ISBN 0-8018-5808-9. A biography in English.
     * Geison L. Geison, The private science of Louis Pasteur, Princeton
       University Press, 1995 ( ISBN 0-691-03442-7). A historical review
       of Pasteur's work
     * Tiner, John Hudson : "Louis Pasteur: Founder of Modern Medicine".
       Mott Media, 1990; ISBN 0-88062-159-1 (paperback). A biography

Influence on medicine and society

     * Latour, Bruno : "The Pasteurization of France". Harvard University
       Press, 1988; ISBN 0-674-65761-6 (paperback). A
       historical/sociological account.
     * Nancy Appleton, The Curse of Louis Pasteur; ISBN 0-9672337-0-4

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