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The Early History of Microbiology

Microbiology is the study of microscopic life on Earth. Today Microbiology has numerous applications in disciplines such as medicine, health-care, environmental science, and food science.

As an independent science, modern Microbiology began in the 17th century with the invention of the microscope. The first microscopes were built by Robert Hooke and Antoine van Leeuwenhoek. Robert Hooke was an English scientist, and he was the first person to use the word cell after using his microscope to observe plant cells. In 1665, Robert Hooke published Micrographia in which he described many of his microscopic observations. Antoine van Leeuwenhoek was a scientist from the Netherlands, who also used his microscope to observe living cells. By using pond water samples, Antoine van Leeuwenhoek was able to document the appearances of microscopic organisms that he viewed with his microscope. The co-invention of the microscope led to a burst of interest in the field of Microbiology.

A direct application of the study of microbes is vaccination, which is the process by which artificial means are used to protect an individual from a specific disease. Modern vaccination began in 1796, when an English physician by the name of Edward Jenner demonstrated that people could be vaccinated against smallpox through exposure to cowpox. Cowpox is a disease in cows that is similar to smallpox in humans. Jenner had made the observation that milkmaids seldom suffered from smallpox. To test his hypothesis, Jenner injected cowpox particles into a young boy and then exposed him to smallpox. The child was protected from smallpox disease, and modern vaccination was born.

The origin of microscopic life was a subject of great debate in the early days of Microbiology. The accepted theory throughout the 17th century and into the 1800s was that of Spontaneous Generation. This theory asserted that living things such as microbes and fruit flies came into existence from nothing. For example if the garbage was left in the street, flies and microbes could arise from nothing to feed on it. This theory was challenged and disproved by Louis Pasteur, a French microbiologist and chemist, in 1861. In a very famous experiment using nutrient broth in a flask, Pasteur demonstrated that the broth would become contaminated and appear cloudy only if it was exposed to air that already contained microbes. Today the flask is on display in France at the Pasteur Museum in Dole. In addition to disproving the Theory of Spontaneous Generation, Pasteur created an anthrax vaccine and developed the process of pasteurization that is still used today to minimize bacterial growth in many food products.

In addition to his work on vaccines and food safety, Pasteur proposed the Germ Theory of Disease. This theory asserted that many human diseases were the result of infection with microbes, as opposed to other non-biological reasons. Pasteur's theory was proven by Robert Koch, a German physician and microbiologist in 1876. Koch demonstrated through experiments with mice, that the microbes taken from mice infected with a bacterium called Bacillus anthracis could be used to infect healthy mice. Bacillus anthracis is the causative agent of anthrax. The steps used by Koch to prove the Germ theory of disease are referred to as Koch's postulates. In addition to proving Pasteur's theory, Koch is also credited with the discovery of Mycobacterium tuberculosis in 1876, and with the development of the pure culture techniques that are still used today to cultivate many species of bacteria in the laboratory.

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