Louis Pasteur (1822-1895) was a prominent French chemist and biologist. He started his career by working with crystals.  He then moves onto his fermentation studies. From these studies, Pastuer invented his technique of pastuerization, or partial sterilization. His findings from his fermentation studies also led him down the road of biology.  The study of microbiology started when Pasteur proved the germ theory of disease.  From here, Pastuer studied and developed vaccines.  His most famous vaccine is the rabies vaccine.  Pastuer, a true scientist, died still contemplating uncertainties in the natural world.
 
 

Two centuries before Louis Pasteur was born, the Scientific Revolution swept through Europe.  During this period, many scientists tried to explain the world with natural physical laws.  The scientific method, using precise experiments and observations, was the most important innovation of this revolution.  Many thinkers, like Francis Bacon, believed science should be used to make nations and people rich.  Unfortunately, the technology was not available for this to begin in the 17th Century.  However, two centuries later, during the lifetime of Louis Pasteur, industry was finally using scientific knowledge directly. Science was becoming a means of wealth.

Also occurring around Pasteur’s lifetime, was the Industrial Revolution (1780-1850).  Many people flocked to the cities and towns that housed the factories.  Poor housing was quickly built with no regards to sanitation.  This oversight led to many diseases and the incentive to discover the ways in which diseases are spread.  The growth of industry also spurred the need for scientists to solve practical problems and make discoveries that the industries could use.
 
 

Louis Pasteur was born in Dole, France, on December 27, 1822.  He was the only son of an uneducated tanner.  Pasteur's father dreamed that his son would become a scholar and gave his son the best education he could.  Surprisingly, Pasteur was only an average student during his early education.  In fact, Pasteur displayed a great talent and passion for drawing and painting during this part of his life.  Although he would eventually stop at age 19, Pasteur’s pictures reveal charicteristics that would one day help him become a great scientist..  All his paintings were very realistic, displaying a great talent for observation and truth.

After Pasteur gave up painting, he became increasingly interested in science.  In 1842 he took the entrance exam for the Ecole Normale Superieure in Paris, a school that trained professors in the arts and sciences.  Pasteur only placed 16th in rank. This position was not good enough for him, and he did not enter.  Instead, Pasteur concentrated on his studies and tried again a year later.  This time he was 5th in rank; he enrolled, specializing in physics and chemistry.  However, this focus did not stop Pasteur from exploring biology later in his life.  It did give him a strong background and discipline in theoretical science, though.

It was at this school where Pasteur made his first important discovery. He was working on his doctorate in chemistry studying the crystals of tartaric acid and its salts. In solution, these tartrates would rotate light, but paratartrates would not rotate light.  This fact intrigued the young scientist.  Another scientist had presented his belief that these two compounds were identical in their make up and crystal forms.  Pasteur knew they could not be identical.  He examined many crystals of each compound under the microscope until he noticed a difference.  All the facets of the tartrates had the same orientation.  In the paratartrates, there were two opposite orientations.  He then separated the two different forms and found that each in solution could rotate light.  Pasteur then proposed that only organic molecules could produce asymmetrical molecules that could rotate light.

In the middle of his work on crystallography, Pasteur was appointed professor of chemistry at the University of Strasbourg in 1848.  Here he met and fell in love with Marie Laurent.  They married on May 29, 1849.  Marie understood her husband's devotion to science and supported him one hundred percent.  She did all she could to help him.  Sometimes, Pasteur would dictate to her, and she would ask for explanations as she wrote.  Marie not only had a general interest, but she understood that it helped Pasteur to discuss his experiments aloud.  Marie eventually bore Pasteur one son and four daughters, three of which would die during Pasteur's lifetime.  Throughout his life, Pasteur remained loving and devoted to his family.

In 1854, Pasteur accepted a position at the University of Lille.  Here, an industrialist asked Pasteur to figure out why lactic acid was sometimes formed instead of alcohol during fermentation.  Pasteur studied the products of fermentation and found that they could rotate light when in solution.  He proposed that the yeast cells, which were thought to be only catalysts, were actually the ones that produced the alcohol.  Pasteur also noticed that alcohol was not produced when there were other microbes mixed with the yeast cells..  Pasteur also discovered and hypothesized that some bacteria could live without air, in fact that air was toxic to the bacteria.  Pasteur went further with this idea, and claimed that organisms have two possible processes for breaking down food for energy.  The first type, the more efficient one, uses oxygen.  The second one does not use oxygen. Fermentation is actually the latter type of respiration.

All these findings later led Pasteur to discover methods of killing the unwanted microbes.  First, Pasteur used antiseptics, but the results were not a successful as he had wished.  He then tried using heat.  In 1864, he found that heating wine to 55^oC would kill the unwanted bacteria, but the flavor of the wine was not altered.  This form of partial sterilization is known as pasteurization, and is still used today.  Pasteur went one step further with his results.  He saw that higher heat could kill off all the microbial life, which is known as sterilization.

While Pasteur was working on fermentation, he left the University of Lille to become the assistant director in charge of science at the Ecole Normale Superieure.  After his fermentation experiments, Pasteur set out to prove that spontaneous generation did not exist.  The success of his experiment was due to the swan-neck flask that would allow air but not dust to reach the solution.  The solution in the flask remained sterile, revealing that air alone can not produce growth of organisms.  When the solution was allowed to touch the dust, microorganisms grew.  The supporters for spontaneous generation were unable to disprove Pasteur's results and this debate finally came to an end.

Pasteur’s fame grew, and in 1865 France's Ministry of Agriculture commissioned him to stop the diseases that were devastating the country's silkworms.  Using his trusty microscope again, he was able to identify healthy worms from those with disease. He suggested using only the healthy silkworms for breeding and taught the silkworm growers how to detect an unhealthy worm. Pasteur also noticed that healthy worms could become infected if they had contact with leaves used diseased worms.  He also found that many factors such as diet, temperature, and sanitation could affect the susceptibility of the worms.  With Pasteur's work, the silk industry in France and other countries revived.

All except Pasteur's first experiment have a common link: microorganisms.  His findings led Pasteur to prove the germ theory of disease, his greatest achievement.  This theory claims that foreign microorganisms directly cause certain diseases. In April of 1864, just before he devised pasteurization, Pasteur was able to reveal the presence of  germs in the air.  A year later, a cholera epidemic broke out in France.  With his colleagues, Pasteur tried to learn the cause and find a cure, but they failed.  Pasteur finally achieved success with disease when he was able to prove the germ theory of disease using anthrax.  This disease was devastating the sheep population all over Europe.  Pasteur grew a culture of the anthrax bacterium, and then repeated growing new cultures 100 times.  This repetition was necessary to make sure it was only the bacterium that was causing the disease.  When the bacteria was injected into the sheep, they developed anthrax and died.  Pasteur went one to reveal that contaminated soil can give the sheep the bacteria.

From this point on, Louis Pasteur devoted the rest of his scientific career to studying diseases.  After anthrax, Pasteur moved on to chicken cholera.  It was during these experiments that Pasteur made one of his most important discoveries.  In 1879, Pasteur injected some chickens with the bacteria that had been stored in the laboratory over the summer.  However, the chickens did not acquire cholera.  When a new fresh batch was injected into these chickens and some others, only the new chickens were infected.  Pasteur understood that this fact occurred for the same reasons that Edward Jenner's vaccination using cowpox was a success against smallpox.

Pasteur believed that vaccination could be used to protect against any disease.  He then set out to grow these vaccines in his laboratory.  The first disease he produced a vaccine for was anthrax.  Pasteur tested the vaccine on June 2, 1881 with complete success.  He had also found a vaccine for rabies, but was reluctant to test it out on humans.  On July 6, 1885 he had no choice.  Joseph Meister, a young boy who had been recently bitten by a rabid dog was brought to Pasteur.  Pasteur vaccinated the boy, and he returned home completely healthy.  Out of Pasteur's first 350 patients to receive the vaccine, only one died.  After this success, the Pasteur Institute was built in France in 1888 to treat rabies victims.  Eventually many other Pasteur Institutes were found in various countries in order to further study disease.

Unfortunately, Pasteur health was failing him by the time the Institute opened in 1888.  Although he could no longer performed any experiments, Pasteur still theorized about the scientific world.  On December 27, 1892, a ceremony was held at the Sorbonne to honor Louis Pasteur and all his achievements.  Three years later, at the age of seventy-two, Pasteur died from additional strokes.  Thousands of people attended his funeral.  His body was entombed in the Pasteur Institute.  Here in 1940 when German soldiers ordered him to open Pasteur’s tomb, Joseph Meister (the young boy who first received the rabies vaccine) committed suicide rather than carry out the order.

Pasteur was not without recognition.   In 1853, he was awarded the prestigious Cross of the Legion of Honor for his scientific accomplishments. Also for his experiments with crystals, Pasteur received the Rumford Medal of the Royal Society of England in 1956.  The French Academy of Science, in 1860, awarded Pasteur with the Prize for Experimental Physiology.  The Academy had been greatly interested in the physiological aspect of Pasteur's work on fermentation.  Two years later, Pasteur himself was elected into the Academy of Science.  For his development of pasteurization, Pasteur was given a Grand Prix medal from the Exposition Universalle in May of 1867.  Even though Pasteur was not a doctor, he was inducted in to the Academy of Medicine in 1873.  In 1881, he is awarded the Grand Cordon of the Legion of Honor, but does not except until his two colleagues are awarded also.  All these medals combined can still not fully expose how much Pasteur's work has meant to the world.   They do not come close to fully describing the honor and greatness of Louis Pasteur.

Louis Pasteur held a complete passion and talent for science.  He overcame the limitations of small inadequate laboratories and equipment.  In fact, Pasteur had to build the polarimeter and goniometer that he used in his first experiment with crystals.  Louis Pasteur would let nothing stop him from his work.  Even a stroke in 1868 that left his left side paralyzed did not prevent him from probing new ideas.  His wonderful discoveries made him national hero and a legend who will not be forgotten.
 
 

Louis Pasteur's achievements had a profound effect on science and everyday life.  The consequences of each of his discoveries are too numerous to discuss in detail.  However, his discovery that only living organism can produce asymmetrical compounds is still being studied today.  His work on fermentation and disease started a whole new branch of biology: microbiology.  His procedure of vaccinations has saved millions of lives.  The germ theory that Pasteur proved completely revolutionized the practice of medicine.  Now sterilization is an essential component to the success of any surgery.  His process of pasteurization allowed milk and other product to last longer before spoiling.  Not only did Pasteur's work on the silkworms and livestock improve people's lives, but it help France's economy and industry.

Pasteur's discoveries and accomplishments are not the only part of his life that has significance.  Louis Pasteur, himself, is significant in history.  He displays the vast success that one human can achieve.  Despite setbacks and limitations, Louis Pasteur prevailed in his noble goal to further science and knowledge.  He is an inspiration to all humanity.
 
 

Dubos, René.  Louis Pasteur:  Free Lance of Science.  New York:  Da Capo Press, Inc., 1960.
Dubos, René.  Pasteur and Modern Science.  New York: Doubleday & Company, Inc., 1960.
Duclaux, Émile.   Pasteur: The History of a Mind.  Philadelphia: W.B. Saunders Company, 1920.
Vallery-Radot, Rene.  The Life of Pasteur.  New York:  Garden City Publishing Co., Inc., 1923.
Windle, Bertram, ed.  Twelve Catholic Men of Science.  London: Catholic Truth Society, 1923.
 
 

http://www.woodrow.org/teachers/chemistry/institutes/1992/Pasteur.html  This site provides an excellent timeline of Pasteur's life.

http://www.louisville.edu/library/ekstrom/special/pasteur/cohn.html   Excellent site on Pastuer's experiments.

http://www.pasteur.fr/pasteur/presentation/IP.html   A site for information on the Pasteur Institute.

http://home.inforamp.net/~schwartz/louis.htm   Nice brief overview of Pasteur's life and discoveries

http://ambafrance-ca.org/HYPERLAB/PEOPLE/_pasteur.html   Very brief discussion of Pastuer's works.

http://www.rockefeller.edu/pubinfo/Pasteur/young_chemist.html   Information about Pasteur's work with crystals.