Table of Contents
Louis Pasteur was born on December 27, 1822, at Dale, Jura France to a poor family. His father was Jean-Joseph Pasteur- a tanner, and his mother was Jeanne Etiennette Roque. Louis Pasteur joined a primary school in 1831, at Arbois. His interests then were fishing and sketching. He went to secondary school at the Collège d’Arbois. In 1839, Louis Pasteur, went to Collége Royal in Besancon to study philosophy. He earned a Bachelor of Letters degree a year later. He tutored at Besancon College while continuing with a science degree course in mathematics. Louis Pasteur did his first exam in 1841 and failed. In 1842, he passed the general science degree but with a very poor grade in chemistry. In the same year, he took an entrance exam for the Ècole Normale Supériere. He had a low ranking and decided to try out the following year. In 1843, he passed the test and joined the institution.
Louis Pasteur got his masters degree in 1845. Later, he joined Balard in 1847 and began his research in Crystallography. Pasteur became a professor of chemistry at the University of Strasbourg in 1848 where he met Marie Laurent. They tied the knot the following year. They had five children, three died of Typhoid before reaching adulthood (Pettinger 2008).
Pasteur became chair of chemistry at the University of Strasbourg in 1854. He began his studies on fermentation at Lille University, where he served as the Dean of the faculty of sciences. He was director of scientific studies at the École Normale Supériere and was appointed a professor of geology, physics, and chemistry at the École Nationale Supériere des Beaux-Arts where he worked until he resigned in 1867. Louis Pasteur then became chair of Organic chemistry at Sorbonne, a position he later gave up due to poor health. In 1887, he established the Pasteur Institute in Paris and was the director until his demise (Trueman 2015).
Jean Baptiste Biot observed that tartaric acid rotated polarized light in 1832. However, the mystery surrounding the compound could not be unveiled since, on one hand, its solution that had been derived from living things rotated the plane of light polarization. On the other hand, its solution derived from chemical synthesis did not rotate the plane, despite the fact that they both had identical chemical properties. Pasteur, after studying tartaric acid, discovered that it consisted of two different types of crystals, which were mirror images of each other. Both solutions rotated polarized light when passed through it but in opposite directions. The effect of rotation was canceled when the crystals were in equal quantities in the solution. His hypothesis, that two molecules with the same atoms and linked by the same bonds can differ in the spatial arrangement of the atoms, later became revolutionary (Schwartz 2001).
Microorganisms Cause Fermentation
Louis Pasteur showed that microorganisms played an important role in fermentation through a series of investigations. Fermentation was a known phenomenon even in ancient times, as it was used in the preparation of bread, wine, and other foods. However, the role that microorganisms played in the whole process was misunderstood (Schwartz 2001). When Pasteur visited a factory, which produced beet juice, he observed that some vats were different. He smelled the first vat; the juice was fermenting into alcohol and smelled fine. However, other vats had a sour odor and a thin layer covered the juice in these vats. This got his attention and he decided to investigate the whole fermentation process. He took samples of the juice with him to his laboratory. When he reviewed the samples with good fermentation using his microscope, there was nothing out of the ordinary, only the yeast cells associated with fermentation. On the other hand, when he reviewed the bad samples under the microscope, elongated black rods replaced the yeast cells. He then performed an experiment, which showed that these black rods were a form of microorganisms, which infected the juice and overwhelmed the yeast cells (Schwartz 2001).
In 1862, after discovering the dangers of fermentation, Pasteur invented the pasteurization process. He realized that just like fermentation, putrefaction was caused by the growth of microorganisms. Before this discovery, no one knew why milk would become sour, and other foods like meat and fish were decaying (Schwartz 2001). The pasteurization process involves heating the product to a certain temperature until the entire harmful bacteria die, making the product to have a longer shelf life. Heating milk to 72 degrees Celsius for 30 seconds, for example, can keep the milk fresh for 7-12 days from the time of pasteurization. At even higher temperatures, the milk can even keep for months without going bad (Woodford 2009/2016).
Germ Theory of Disease
The theory states that specific microorganisms cause specific diseases. Previous theories, such as the spontaneous generation theory, stated that life originated spontaneously from non-living things, a theory that Pasteur strongly disapproved. In an effort to disapprove the theory, he invented the germ theory of disease. He, therefore, carried out an experiment. He took two swan-neck flasks containing liquid broth and boiled them. He broke the neck of one flask and left the other as it was. The broth in the broken flask became cloudy while the broth in the other flask remained as it was. The cloudy flask indicated growth of microbes. This is because the dust entering the flask, whose neck was not broken, got trapped and did not reach the broth, unlike in the broken flask, which allowed dust into the broth, thereby introducing the microbes. This experiment demonstrated the existence of germs in the air (the dust particles). It also proved the spontaneous theory was wrong and it laid the ground for microbial theory. Louis Pasteur also gave demonstrations on how to cultivate bacteria and premises for a culture of viruses on animal tissues. He laid the foundations for infectious epidemiology through his demonstration on how pathogens spread through animal and human populations.
Immunology and Vaccination
After discovering microbes as the cause of diseases, he introduced the concept that vaccination could be used for microbial diseases (Smith 2012). In 1879, fowl cholera disease was rampant in chicken. The disease was caused by a bacterium known in the present day as ‘pasturella’. Several drops of a culture of these bacteria inoculated into a chicken were enough to kill it. However, Pasteur observed that chicken inoculated with an old culture did not die and were also protected against inoculation by a virulent culture later on, thus the discovery of vaccination (Schwartz 2001). He then applied this principle to other diseases repeatedly. Pasteur, later on, discovered the vaccination against anthrax, at a public experiment carried out in 1881 at Pouilly le-Fort. In this event, 24 sheep were vaccinated and 24 others were not vaccinated. All of them were then given the anthrax bacillus injection. The vaccinated sheep survived while all the unvaccinated sheep died. Pasteur also discovered the rabies vaccine. The vaccine was successfully used on Joseph Meister on July 6, 1885, and Jean-Baptiste Jupille in October that year (Schwartz 2001:598).
Helped Save the French Silk Industry
The silk industry was being destroyed slowly because of a disease that had been killing the silkworms. In 1865, Pasteur was asked to investigate the disease in order to control it as it was badly affecting the industry. He discovered that the disease, Pebrine, was caused by microorganisms. He also discovered that the healthy silkworms become sick when they nested on the sick silkworm’s beddings. Pasteur observed that the environment influenced contagion of diseases and recommended sterilization as a preventive and control measure.
In conclusion, despite the success of his work, Pasteur faced a number of challenges and criticism along the way. As the director of Ecôle Normale, while studying liquids like milk and wine, he was convinced that the samples he studied were contaminated with microbes floating in the air. The institution ridiculed him saying the experiments he was performing would turn against him. Dr. Charlton Bastian maintained his belief that putrefaction came from within and to from invading microorganisms, even after proving his case in front of a gathering of famous scientists in 1865. In the same year, when a cholera epidemic hit Marseilles, he performed a number of experiments hoping to discover the germ that caused the disease but was unsuccessful. He suffered a brain hemorrhage, which affected the left side of his body in 1868. This affected his work. His works, by this time, had inspired other scientists such as Robert Koch, who later came up with the Koch’s postulates (Trueman 2015).
with any paper
- “Louis Pasteur (1822–1895): The Master of Microbiology.” 2017. Pioneers in Microbiology, 49-68. doi: 10.1142/9789813200371_0007
- Pettinger, T. 2008. “Louis Pasteur Biography.” Retrieved January 29, 2018, from https://www.biographyonline.net/scientists/louis-pasteur.html
- Schwartz, M. 2001. “The life and works of Louis Pasteur.” Journal of Applied Microbiology, 91(4), 597-601. doi:10.1046/j.1365-2672.2001.01495.x
- Smith, K. A. 2012. “Louis Pasteur, the Father of Immunology?” Frontiers in Immunology, 3. doi:10.3389/fimmu.2012.00068
- Trueman, C. N. 2015. “Louis Pasteur.” Retrieved January 29, 2018, from http://www.historylearningsite.co.uk/a-history-of-medicine/louis-pasteur/
- Woodford, C. 2017, August 09. “Pasteurization of milk and food.” Retrieved January 29, 2018, from http://www.explainthatstuff.com/pasteurization.html