Beer, wine make Pasteur leading germ theory champion

Many Americans may know the name Louis Pasteur because of the notice of pasteurization on their milk, but few may know that pasteurization was first applied to wine and beer. Fewer still may realize the impact Pasteur had on germ theory, the idea that every disease is caused by a specific microorganism, which is the central tenet of today’s medicine (1-5).

Louis Pasteur was born in France in 1822. By the age of 32 Pasteur had earned a doctorate in chemistry and a faculty position at the University of Lille. The faculty were asked to use their expertise to solve practical problems and when the father of one of Pasteur’s students, a local distiller, asked for help Pasteur jumped at the opportunity. At the time it was understood that sugar fermentation produced alcohol but it was thought to be a purely chemical process and the yeast identified in beer and wine a product or catalytic agent of fermentation. The problem posed to Pasteur was to find the cause of sour wine and beer. Pasteur confirmed the presence of yeast in these cultures but also of bacteria. Using his experise on crystal structures, Pasteur was able to determine that yeast were responsible for the fermentation process and that bacteria present caused the souring of the alcohol. The solution was simple: boil the liquid for a few minutes and then add a pure culture of yeast to start the fermentation process (1-5).

Not only did this finding save the wine industry from the seemingly sporadic losses of batches, but it proved to Pasteur that the theory of spontaneous generation was wrong. Since ancient times it was believed that insects and (later) microbes arose from rotting matter as a biproduct. It was clear to Pasteur that microbes were present in the air and on the surface of grapes in the vineyards and thus present in distilling cultures. In an exploratory experiment Pasteur found that city air grew more cultures than air from high altitudes. A simple, yet elegant, experiment followed that proved germ theory’s dominance over spontaneous generation. Pasteur sterilized a fermentable liquid in a flask. The neck of the flask was heated and bent into an s-shape and sealed. The solution remained sterile. After the neck tip was broken off the solution yet remained sterile as the particles in the air were trapped on the beads of water sticking to the glass neck. Only when the flask was tipped to allow the solution to contact the trapped particles in the neck did a culture grow (1-5).

The surgeon Joseph Lister, in England, embraced Pasteur’s find and sterilized the equipment and air in his operating room. This dramatically reduced fatalities and caused Lister to champion germ theory as well. And yet most scientists clung to spontaneous generation until the 1870s and 80s (1-5).

Pasteur continued his research, identifying diseased silk worms and the conditions that contribute to their condition, saving the French silk industry. He also used Robert Koch’s discovery of the spores that cause anthrax to develop a vaccine for farm animals. A public challenge in 1882 by veterinarian Rossignol was a success, with Pasteur showing that 25 vaccinated sheep survived anthrax infection while 25 unvaccinated sheep perished. The circus-like atmosphere only helped the case of germ theory; dispatches were sent around Europe detailing his success. The vaccine not only resulted in reducing the mortality rate of livestock to 1% but also in monetary savings to France over the next 10 years totalling an estimated $7 million francs (1-5).

Pasteur’s swan song a few years later was developing a vaccine for rabies. Initial experiments were in rabbits and dogs and involved drying and mincing infected animals’ spinal cords and injecting the material, on a graduated scale of least to most potent, under the skin of healthy animals over several days. At the end of the trial the treated animals were immune to rabies. The news traveled quickly and in 1886 Pasteur found himself in an ethical quandary. A young boy, Joseph Meister, had been bitten and mauled by a rabid dog. Although Pasteur had great success with animal vaccination he was not completely confident in the vaccine’s use for humans. The boy’s mother pleaded and Pasteur began the vaccine trial. Meister recovered completely (1-5).

This success led to the establishment of the famed Pasteur Institute in Paris, initially a hospital to treat human rabies (1-5). In 1895 Pasteur died after a series of strokes since his 40s. He was given a state funeral having contributed immeasurably to the health and industries of France and pioneering germ theory. Joseph Meister grew up to work as a gatekeeper at the Pasteur Institute (5). In 1940 Nazi invaders ordered Meister to open Pasteur’s crypt. Sadly, Meister refused and committed suicide.

1. http://www.bbc.co.uk/historic_figures/pasteur_louis.shtml
2. http://louisville.edu/library/ekstrom/special/pasteur/cohn.html
3. http://encarta.msn.com/text_761568595___0/Louis_Pasteur.html
4. http://www.fordham.edu/halsall/mod/1878pasteur-germ.html
5. http://elane.standford.edu/wilson/Text/5f.html