His Life and His Works
Louis Pasteur was a chemist but can also be thought of as a bacteriologist, a
biologist and a pathologist for his important contributions in these areas. He
was born on December 27 1822 in Dole, in the region of Jura. He said to
have always been a scientist at heart but believed that there were some
spiritual morals that were of greater importance. He was also a very eloquent
speaker, perfectly capable of defending his own points and during the course of
his life, he taught in Dijon, Strasbourg, Lille and Paris at the `Ecole Normale
Superieure` and the Sorbonne (1867-1889). In 1888, the Pasteur Institute was
founded in Paris, with Pasteur at its head, to continue teaching and research
into infectious diseases. He died in 1895.
Pasteur is well known for his discovery that the most infectious of diseases are caused by germs, each disease having its own specific germ. This was his revolutionary `germ theory of disease`. This may sound a bit silly to many people nowadays "of course there must be germs or why would we get ill in the first place?" I hear you say. However, one must bear in mind that up until then the recognized `theory` was that of spontaneous generation of diseases. Indeed, in Pasteur's time, many still thought that diseases were simply punishments from the goods for their sins. Pasteur's theory set the stage for all of modern medicine and forms the basis of all further microorganism studies.
Pasteur's earliest work was carried out on tartrates and the effect of tartaric acid on polarized light. He discovered in 1848 that there were in fact 2 different tartrate crystals which had opposite effects on polarized light: when the light was shone through the crystal, it was seen that the 2 different crystals caused the plane of the polarized light to be rotated in opposite directions. This is the only difference between chemical enantiomers, even known today, and Pasteur can be thought of as the real father of stereochemistry for he is the first to have discovered molecular dissymmetry.
Pasteur's work on enantiomers was soon expanded to more practical applications. Indeed, he discovered that yeast existed in the form of two different enantiomers and studied the various effects of these two during alcohol fermentation. Fermentation of yeast produces alcohol and so was used for the preparation of beer and wine. Pasteur discovered that if left in after fermentation, one enantiomer would cause the drink to turn sour. This also led to him finding out that yeast is a living microorganism and that gentle heating would kill it preventing the alcohol to turn sour. Students therefore owe Pasteur a huge debt! This was the start of pasteurization.
Pasteur's studies of microorganisms led to the discovery and study of bacteria. He was then able to establish his `germ theory of disease` and begin isolating various bacteria responsible for various infections. These discoveries were of huge economic value. Pasteur discovered bacilli for 2 different silkworm diseases which saved the French silk industry from ruin, the infected worms being able to be isolated and destroyed and a method to prevent the spreading of the diseases found.
He also discovered the bacterium responsible for anthrax as well as that for chicken cholera and developed effective livestock inoculations. He discovered the effect of these inoculations, which he termed vaccines, by running an anthrax test on 50 sheep. 25 were injected with a heated strain of anthrax, before submitting all 50 to the real disease. The 25 pre-treated sheep survived whereas the others did not. This showed that heated diseases lost their potency but could confer immunity. One of his most important vaccines was that for treatment of rabies in dogs and humans, which was successfully demonstrated in 1885. Whilst studying the case of rabies, he discovered that it was transmitted by carriers that were too small even to be seen under a microscope. Thus he made the first step into the world of viruses.
In his book `The Germ Theory and its Application to Medicine and Surgery`, Pasteur urged and challenged doctors to take sanitary measurements, such as washing their hands, using clean instruments and disinfecting their materials.
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