A father of microbiology
Few people have saved more lives than Louis Pasteur. The vaccines he developed have protected millions. His insight that germs cause disease revolutionised healthcare. He found new ways to make our food safe to eat.
Pasteur was the chemist who fundamentally changed our understanding of biology. By looking closely at the building blocks of life, he was at the forefront of a new branch of science: microbiology.
27 December 1822
The artist who became a chemist
Louis Pasteur was the son of a sergeant major in the Napoleonic wars who grew up with a passionate love of his native France.
Pasteur spent his childhood in the Jura mountains in eastern France. He was an average student with a passion for drawing and painting. As a boy, he captured his family in a series of lifelike portraits which showed a keen eye for precision and detail. While his teachers encouraged his artistic side, his father considered painting an indulgence: what counted was solid schoolwork. So Pasteur studied hard.Arbois: Pasteur's childhood home
In teaching me to read, you made sure I learned about the greatness of France.
A startling discovery about the building blocks of life
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Pasteur began a career in chemistry with a post at the University of Strasbourg. He quickly made a ground-breaking discovery.
Pasteur showed that otherwise identical molecules could exist as mirror images (or 'left' and 'right-handed' versions.) He noticed that molecules produced by living things were always left-handed. This discovery was a fundamental step forward in microbiology, underpinning modern drug development and even our understanding of DNA. Aged 25, Pasteur had made arguably his most profound contribution to science.How can pasta help us understand asymmetrical molecules?Why is life on Earth left-handed?Why symmetry matters: The story of thalidomide
Disproves a theory held since Aristotle
Pasteur's training in chemistry helped him solve one of the biggest questions in 19th century biology.
For two thousand years, people thought life appeared spontaneously, believing fleas grew from dust, or maggots from dead flesh. Pasteur finally disproved this theory in an elegant experiment. He showed that food went off because of contamination by microbes in the air. He went on to argue that these could cause disease. His 'germ theory' was controversial, not least because he was a chemist not a doctor, but led to the development of antiseptics and changed healthcare forever.Bitesize: Joseph Lister and antiseptic surgeryFlorence Nightingale pioneers cleanliness in hospitalsWhy people believed in spontaneous generation
I am afraid that the experiments you quote, M. Pasteur, will turn against you. The world into which you wish to take us is really too fantastic.
Pasteur had made his name with germ theory. Now Napoleon III came to him with a tricky problem facing France's wine industry.
Good French wine was prized around Europe. Yet vineyards were losing money when bottles spoiled in transit. Pasteur realised this was due to contamination, but boiling wine to kill bacteria made it taste terrible. In a series of careful experiments, Pasteur discovered that heating wine to 55 degrees killed bacteria without ruining the taste. This process, later named pasteurisation, saved the wine industry, and cemented Pasteur’s fame. Today, it’s widely used to keep food free from disease.Bitesize: How milk is pasteurised
A bottle of wine contains more philosophy than all the books in the world.
Rescues the silk industry
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Pasteur had saved the French wine industry. Now he was asked to help its silk industry which faced a crisis caused by a mysterious silkworm disease.
The eminent scientist protested he’d never touched a silkworm in his life. Yet he saw an opportunity to investigate the role that microscopic organisms play in illness. He devoted six years to the study, assisted by his wife Marie, who bred silkworms for experiments. He worked out that infection was transmitted by parasites, and showed how infected worms should be isolated and destroyed. His advice meant the silk industry survived, providing another boost to France's economy.Who was Marie Pasteur?Pasteur’s silkworms at the Science MuseumHow silk made France rich
At this point, Pasteur’s career does seem to have been guided by the special providence that watches over a genius.
Aged 45, Pasteur suffered a stroke which partially paralysed his left side. Colleagues set up a mobile laboratory so he could work from his sickbed.
This dedication was characteristic of Pasteur, who had thrown himself into work when faced with personal losses. He lived in an age when children often died from infectious diseases. In 1859, Pasteur had lost daughter to typhoid – a disease caused by dirty food and water. In 1865, his second daughter died of the same disease. A third daughter died from a tumour in 1866. Family tragedy framed his fight against illness.
The only thing that can bring joy is work.
A chance observation in the chicken coop
Pasteur’s new ideas about infectious diseases led him and his growing team to study chicken cholera. Here he made another landmark discovery.
After a month away from his lab, Pasteur injected an old culture of bacteria into his chickens. The birds fell ill, but did not die as expected. And now they were resistant to fresh cholera injections. Pasteur realised weakened strains of a disease could help animals develop immunity. A century before, Edward Jenner had found that cowpox protected against smallpox. Now Pasteur had found a way to create vaccines in the lab. It was a turning point in the fight against infectious disease.Who was Edward Jenner?NHS: How vaccines work
Trials a vaccine for anthrax
Pasteur was keen to develop vaccines for other diseases. He turned his attention to anthrax.
Anthrax was fatal to humans, and could wipe out entire populations of farm animals. Anyone who could prevent the disease would not only save lives, but also stood to make money. German doctor Robert Koch had already found the bacteria that caused the disease. Now Pasteur announced he'd discovered a vaccine, and successfully immunised 31 animals – although recent studies of his notebooks have revealed he exaggerated how much original work he did; he'd actually drawn on other people's findings.Robert Koch: the other founding father of microbiologyPasteur and Koch: a rivalry fuelled by nationalism
Vaccinates a boy against rabies
Pasteur now turned his attention to rabies – a fatal disease with gruesome symptoms which caused a long and painful death.
Pasteur had trialled a vaccine on dogs, but was nervous about testing on humans. He faced a dilemma with Joseph Meister, a boy bitten by a rabid animal. It wasn't certain that Joseph would develop the human form of rabies, but Pasteur went ahead and tested his treatment anyway. Joseph survived. The first human trial of a man-made vaccine was another landmark, although when Pasteur later wrote up his experiments, he exaggerated again, saying he'd done more animal testing than he really had.Pasteur's original report to the French AcademyPasteur ‘told lies about vaccines’
The Pasteur Institute founded
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People were desperate to be inoculated against rabies. If Pasteur was to satisfy this demand and continue research on new treatments, he needed help.
Pasteur made an international appeal for funds, and set up a charitable body, the Pasteur Institute, whose purpose was to continue research into infectious disease. Work begun by the institute saved many lives. French economic – and colonial – expansion depended on the ability to fight new diseases and new branches of the Institute opened in French colonies such as Senegal and the Ivory Coast.History of Pasteur Institute
Pasteur paves the way for eradication of diptheria
Wellcome Library, London
One of the first successes of the newly formed Pasteur Institute was a breakthrough in the fight against diphtheria - a major childhood killer.
Two of Pasteur's earliest appointments were his former assistants Emile Roux and Alexandre Yersin. The two men identified how diphtheria caused disease by flooding the body with toxins. The work was a key step towards finding a treatment and eventually a vaccine. The fight against diphtheria is one of medicine's big success stories. Today, around 85% of children around the world are immunised. Through the work of scientists such as Roux and Yersin, Pasteur's legacy would live on.Who was Pierre Paul Émile Roux?NHS Choices - Diphtheria
28 September 1895
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Pasteur continued to run the Pasteur Institute in Paris as his health deteriorated. Following another stroke his paralysis worsened. He died aged 72.
France mourned the loss of a national hero. Pasteur was buried in Notre-Dame cathedral. The following year his remains were transferred to a purpose-built crypt in the headquarters of the Pasteur institute. His wife was buried alongside him when she died in 1910. Today, Pasteur is remembered as one of the founders of preventative medicine. The work he began continues to save millions of lives around the world.NHS: are vaccines safe?