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Louis Pasteur (December 27, 1822 - September 28, 1895)
was a French scientist who was a pioneer in microbiology.
Louis Pasteur was born in Dole, Jura département, France, the son of a tanner. He was admitted in 1843 at the École Normale Supérieure and got a doctoral degree in 1846.
In his early work as a chemist he resolved a problem concerning the nature of
tartaric acid. A solution of this compound derived from one source
rotated the plane of polarization of light passing through it. The mystery
was that tartaric acid derived by synthesis had no such effect,
even though its reactions were identical and its composition was the same.
Pasteur noticed, upon examination of the tiny crystals of tartaric acid, 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 polarised light clockwise; the other form rotated light anticlockwise; and
an equal mix of the two had no effect on polarized light. Pasteur correctly deduced that the tartaric acid molecule was
asymmetric and could exist in two different forms that resemble one another as a left- and right-hand glove resemble one another.
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.
His doctoral thesis on crystallography got 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 1857, he was
made administrator and director of scientific studies of the École Normale Supérieure.
He demonstrated that fermentation and the growth of microorganisms in nutrient broths were not due to spontaneous generation. He exposed freshly 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 being
spontaneously generated within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and developed germ theory.
With this established, he invented the process of pasteurization, in
which liquids such as milk were heated to kill all bacteria and molds already present within them. He and Claude Bernard
completed the first pasteurization test on April 20, 1862.
His 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, although they had not actually caused the disease.
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 than with the naturally acquired disease.
Edward Jenner had also discovered vaccination, using cowpox to give cross-immunity to smallpox, and by
Pasteur's time this had generally replaced the use of actual smallpox material in inoculation. The difference with chicken
cholera was that the weakened form of the disease organism had been generated artificially, and so a naturally weak form
of the disease organism did not need to be found.
This discovery revolutionised 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, which was first used on 9-year old Joey 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. Fortunately, the treatment proved to be a spectacular success, with Joey avoiding the disease. So 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.
Pasteur died in 1895 from complications caused by a series of strokes that had begun plaguing him as far back as 1868. He was
buried in the Cathedral of Notre Dame, but his
remains were soon placed in a crypt in the Institut Pasteur, Paris.
External links
Also work on anthrax, silk worm diseases and brewing that I can't remember offhand. Perhaps someone else can fill
in.
His work with silk: In 1865, Pasteur set out to help the silk industry. A disease called pebrine was killing great numbers of
silkworms. He worked several years to prove that a microbe that attacks silkworm eggs causes the disease. He showed that
eliminating this germ in silkworm nurseries would wipe out the disease.
If they'd had the Nobel Prize back then, there's no doubt Louis would have
been a hot contender for the Chemistry, Biology and Medicine prizes. He did, however, win the Leeuwenhoek medal, microbiology's highest honor, in 1895.
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