Louis Pasteur – A Pioneer: Contributions of Pasteur to the Development of Microbiology

Louis Pasteur, one of the greatest scientists the world has seen, was born on December 27, 1822, in Dole, France. His father was a poor tanner but he wanted Louis to get a good education. Pasteur attended school in a nearby town called Arbois. His headmaster saw potential in him and encouraged him to go to Paris to further his education.

Early Life of Louis Pasteur

Pasteur’s first sojourn to Paris did not go too well. He got homesick and came back to study in a town called Besancon, where he received degrees in Letters and Mathematical Sciences. He got admitted to an elite college in Paris called Ecole Normale Superieure. He obtained his doctorate degree in 1847 and a year later he became professor of Chemistry at the University of Strasbourg. He courted and married Marie Laurent, the daughter of the University Hostel’s Rector, in 1849.

Birth of Stereochemistry

Pasteur’s first landmark contribution was to the field of chemistry where he showed the presence of chiral molecules of sodium ammonium tartarate. Chiral compounds have the same molecular formula but they are mirror images of each other. This discovery triggered the search for chiral molecules of many other compounds giving rise to a new branch of chemistry called Stereochemistry. In 1856, he was made the administrator and director of scientific studies at Ecole. By 1857, Pasteur had become a world famous scientist.

Pasteurization

During his time at the University of Lille, Pasteur was approached by the wine manufacturers of the region. They were concerned about many recent batches of their wine turning sour and this problem was seriously affecting the reputation (and profits) of the famous French Wine Industry. Careful analysis by Pasteur showed that a bacterium had “contaminated” the wine fermentation batches and was producing an acid which was resulting in souring of the wine.

He found out that gentle heating of the wine to around sixty degrees centigrade for about thirty minutes was enough to destroy the bacterium and prevent souring. This came as a great relief for the French Wine Industry and also helped Pasteur’s reputation go far and wide. This technique of Pasteur’s was applied to other beverages as well and particularly to milk where it came to be known as pasteurization.

Discovery of Germ-Disease Relationship

Pasteur also rescued the French Silk Industry which was plagued by a disease called pebrine which affected the caterpillars which died before making their cocoons. Pasteur found out that the disease was caused by a bacterium. He thus found out the connection between bacteria and diseases. He worked with the silk industry to devise methods to keep their hatcheries bacteria-free and thus, disease-free.

Discovery of Attenuation

One of the most important discoveries of Pasteur is, without doubt, attenuation. He was working on a disease which plagued chickens and was affecting the poultry farmers of France. This disease called “chicken cholera” was caused by a bacterium. Pasteur isolated the bacteria from diseased chickens, cultured them outside and when he inoculated this fresh culture into healthy chickens, they developed the disease and died. Legend has it that he left a bottle of culture in his laboratory and went for a couple of weeks’ vacation. When he returned, he inoculated the “old” culture into healthy chickens. The chickens became sick but recovered, much to the chagrin of Pasteur who had expected them to die.

Pasteur then inoculated fresh “virulent” bacterial culture into the same chicken, which surprisingly, failed to die. Pasteur deduced that the bacterial culture had lost its “virulence” or disease-causing ability and had been “attenuated.” This forms the basis of vaccination. Pasteur applied this technique to help protect sheep from anthrax, another fatal bacterial disease. But Pasteur is best remembered for his work on the rabies vaccine, the first human vaccine.

The Rabies Vaccine

Pasteur inoculated the fluid taken from a rabid dog that had just died, into a rabbit. The rabbit developed rabies and died. Pasteur removed the spinal cord of the rabbit, dried it and powdered it. He injected this into a healthy rabbit, which was later inoculated with the virulent inoculums. The rabbit failed to develop rabies. The first person on whom the rabies vaccine was tested was a young boy named Joseph Meister. The boy repaid the benevolence of Pasteur by returning to Paris and working for him. When Meister was key keeper of the Pasteur Institute in Paris, the Nazis raided it and forced Meister to hand over the keys of Pasteur’s crypt. Instead of handing over the keys and betraying his benefactor, Meister shot himself.

Pasteur dedicated his entire life to the goodwill of humankind. He faced personal tragedies during his life with three of his five children dying at a young age. It is a general belief that had the Nobel Prize been instituted earlier, Pasteur would have won it a number of times for his various important contributions. Pasteur died on September 18, 1895 from complications arising from a stroke he had suffered a few years previously.

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