SOMETHING TO CONSIDER

The Legacy of Louis Pasteur

BY GARY LATTA

Few individuals in history can get close to equaling the achievements and contributions to mankind than those of Louis Pasteur. Most people associate Pasteur with the term that bears his name: “pasteurization,” but there is so much more that he achieved throughout his life that benefitted the world and advanced science. In January 2022, the United Nations World Food Program honored Pasteur as the “father of microbiology,” responsible for several amazing and world-changing discoveries. Not only was he a pioneer for food safety but also a great experimenter and innovative theorist whose breakthroughs have saved countless lives.

Pasteur was born in 1822 in the town of Dole, France, about 248 miles southeast of Paris. His family had operated a tannery for generations, and it was assumed young Louis would carry on in the tanning business. However, he showed great aptitude for learning and his thirst for higher education was recognized by his early teachers. At age 15, he traveled to Paris to complete his secondary education. Later, Pasteur completed his Bachelor of Science at the Royal College of Besancon in 1842. To further his education in chemistry, he attended the Ecole Normale in Paris, receiving his Master of Science in 1845.

Pasteur then pursued his doctoral degree at Ecole Normale where he investigated the structure of tartrate and paratartrate crystals, whose structure had baffled the greatest chemists of the time. By the time he received his doctorate in 1847, Pasteur was developing a reputation among research scientists. In 1848, he

Throughout his life, Pasteur took little money for his discoveries. While he did patent many of his works, he sought no compensation, believing his breakthroughs should be gifts to mankind.

became a professor of chemistry at the University of Strasburg and spent five years teaching and conducting research there. In 1854, Pasteur was appointed professor of chemistry and dean of the science faculty at the University of Lille. He was asked to establish a science faculty and do research there for the benefit of industry and business. At Lille, Pasteur’s research in applied science led him to explore the process of fermentation, which turns sugar into alcohol and sours milk. A new branch of science called microbiology was born. Pasteur had proved that fermentation took place from tiny living organisms called microbes. In 1857, he returned to Ecole Normale as Director of Scientific Studies where he continued his work on microbes.

At the time, most scientists believed in the concept of spontaneous generation of microscopic organisms. Spontaneous generation embraced the thought that life can spring up from non-living matter such as worms, mice and maggots. This idea was later disproved when meat wrapped in gauze prevented flies from laying eggs on the surface. Maggots are the larvae from fly eggs that hatch.

Pasteur created custom glassware in his lab where he could boil broth to kill any microbes present. His special glassware would allow air to circulate around the broth but not allow airborne microbes to enter. As he expected, no microbes appeared later in the broth. Pasteur had proven that microbes were not generated spontaneously in the broth itself but only appeared if allowed to enter with the air. Microbes, like other living beings, came only from life itself and were not spontaneously generated.

Armed with a decent theoretical understanding of microbes, Pasteur applied his findings to the important French wine industry. In 1865, the French economy was highly dependent on wine exports, and many citizens relied on the industry for its livelihood. Wine souring and spoilage was a persistent problem that Pasteur tackled by slightly modifying his glass broth jars. Boiling the wine altered its flavor, so Pasteur heated it just enough to destroy most of the microbes without altering taste. He found that by quickly chilling, and then preventing air from entering, the wine had little additional microbial growth. Pasteur was ecstatic in finding that this same process could be applied to milk. His discovery made milk, wine, beer and many other products safe for consumption and wider distribution.

Following his fermentation discoveries, Pasteur turned his attention to germ theory. He and a few other researchers believed diseases were caused by microorganisms or “germ theory.” His opponents at the time believed major diseases were the result of an individual’s weak and imbalanced state. In 1868, Pasteur turned his attention to another major French industry — silk. Silkworms were being destroyed due to diseased eggs. Pasteur trained silkworm farmers in the use of the microscope to detect diseased eggs, which could then be destroyed. France and its silkworm nurseries were saved! Pasteur was a national hero and by this time was developing quite a bit of fame. The French government honored him with the Legion of Honor, its highest award.

In 1880, Pasteur carried on his work against disease. This time focusing on fowl cholera. His research led to the discovery of microbe attenuation or weakening to create vaccines. He found that injecting weakened attenuated microbes into the chickens protected the poultry from the onslaught of disease and almost certain death from fowl cholera.

Pasteur began to realize that his discovery of injecting with attenuated microbes could be applied to other diseases. This time, he turned his attention to anthrax and soon realized that weakened bacilli would protect sheep and other farm animals. In a famous public display at Poultry-le-Fort in 1881 before a large crowd, Pasteur vaccinated a group of sheep, goats and

cows with his new vaccine. A control group of similar animals were not vaccinated. All animals were then injected with a virulent anthrax bacillus. A few days later, the crowd reassembled, and Pasteur was met with resounding applause. All the inoculated animals were alive, while the control group of other animals were dead or almost so. The effectiveness of his vaccine was undeniable.

Not resting, or taking any time off, Pasteur turned his attention and active mind to his next theoretical breakthrough – the concept that many animal diseases were the result of harmful microbes or germs. He believed the microbes entered the body and multiplied. In 1882, Pasteur advanced to the next, and likely the greatest, step in his career – diseases in humans. Pasteur explored diseases that afflicted both animals and humans. This way he could conduct research using animals first. He turned his attention to rabies.

Throughout history, rabies was a feared and deadly disease contracted by being bitten by a dog, wolf or other animal. Treating humans was performed by cauterization of the wound with a hot iron. This method rarely worked, and most patients later died.

Pasteur started his rabies research with animals in 1882. He was frustrated by the long incubation period between the time the animal was bitten and the time it took for the germs to enter the brain. Research was time-consuming but led to another remarkable discovery. Previous research revealed that vaccines must be given prior to exposure. The delay in time that it took for the rabies germ to reach the brain meant that a vaccine could be administered after exposure from a bite. So only those who had been bitten by a rabid animal need be treated.

Pasteur discovered that like other infectious diseases, rabies could be attenuated or weakened before injecting into another animal. Attenuated rabies was injected into rabbits, monkeys and later dogs with success against later death. In 1885, a 9-year-old boy was bitten by a rabid animal. With some reluctance, Pasteur agreed to treat his first human, who was otherwise faced with certain death. He was not sure if the vaccine he created would be effective with humans. Following several weeks of treatment, it became clear the vaccine used on the boy was successful. Pasteur had achieved world renown.

In 1888, the Pasteur Institute in Paris was formed as one of the most premiere facilities of biomedical research work against disease in the world. By this time Louis was nearing 66 years old. With failing health, he served the institute in an advisory capacity with scientists he had trained. His students assumed future responsibilities and carried on his research.

Throughout his life, Pasteur took little money for his discoveries. While he did patent many of his works, he sought no compensation, believing his breakthroughs should be gifts to mankind. Pasteur died on Sept. 28, 1895, after a remarkable life. His numerous contributions to science and medicine are impressive. He often said that his strong Christian faith supported him through many challenges and trials. Pasteur was a strong believer in creation and was staunchly opposed to Darwin’s theory of evolution.

Today, the pharmaceutical company Sanofi Pasteur continues his legacy of discovering and manufacturing vaccines.

Gary Latta is a dairy product specialist consultant for the Northeast Dairy Foods Association, Inc. He has more than 30 years of experience in providing economic analysis, statistics and information to the dairy processing industry.