The Petri Dish is one of the most important devices in a laboratory of microbiology. It is efficient and, at the same time, simple. It can be described as a glass or plastic cylindrical, container, with vertically raised edges. A Petri Dish can be covered by another one,in the same format, a little bigger.
The eponym refers to Julius Richard Petri, a German microbiologist, who idealized the device when he was assistant of Robert Koch in the 1880s.
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| http://hardydiagnostics.com/articles |
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| Julius Richard Petri (1852-1921) Wikipedia |
In the last quarter of the nineteenth century, the germ theory bloomed, which revolutionised medicine. And Robert Koch was one of the greatest exponents. Isolating the bacteria was a very difficult process. The culture medium, usually liquid and in a flask, was often contaminated and did not enable replication.
A big step in the tecnique of bacteriological culture was in 1881, when Fanny
Angelina Hesse, also an assistant of Koch, discovered a way of making an efficient and solid culture medium, using agar. Immediatelly, Koch started to use agar (he used jelly before that) infused with meat broth in a glass dish, covered by a bell jar. This provided a larger area to spread the cultures and also to facilitate isolation of colonies, but the device was contantly exposed to the air and was easily contaminated.
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| Robert Koch (1843-1910) Wikipedia |
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| Fanny Angelina Hesse – (1850-1934) Wikipedia |
In 1887, Julius Petri had the idea of building a wall perpendicular to the dish’s surface and also of covering it with another dish, a little bigger, which would block the contact with the air and keep the oxygen. The Petri Dish continues to be extremely useful in laboratories of microbiology and it’s design remains almost unchanged, nearly 130 years after the invention of it.
The Petri Dish, the agar of Fanny Hesse (who did not have the deserved eponym) and the genius of Koch enabled a huge progress in the development of Bacteriology, consolidating Germ’s Theory and establishing one of the greatest revolutions in the history of medicine.
Translated by Ana Raquel Costa Geraldes
Translated by Ana Raquel Costa Geraldes
