Who Discovered E. coli? Theodor Escherich and the History of E. coli

If you have ever asked who discovered E. coli, the answer is Theodor Escherich, a German-Austrian pediatrician, who first described it in 1885. He was not looking for a famous laboratory workhorse. He was studying the bacteria in the intestines of newborn babies, and among them he found a common rod-shaped organism that he named Bacterium coli commune.

Figure: Logo of Nobel Prize with computer generated image of E. coli

More than a century later, that same bacterium is the best-known organism in all of biology: in many ways we understand E. coli better than we understand ourselves. This article tells the story of its discovery and how it became the most important tool in modern biology.

Who discovered E. coli?

E. coli was discovered in 1885 by Theodor Escherich (1857–1911), a German-Austrian pediatrician working in Munich. Escherich was studying a question in infant health: how the sterile gut of a newborn becomes colonized by bacteria in the first hours and days after birth. To do this, he examined the feces of healthy babies under the microscope and grew the bacteria he found using the new pure-culture and staining methods of the day, including Gram's staining technique.

Among the organisms he found was a short, rod-shaped bacterium present in large numbers in the healthy infant gut. He named it Bacterium coli commune: "coli" because it lived in the colon, and "commune" because it was so common. He presented this work in a lecture on July 14, 1885, and published it that year.

When and how was E. coli named?

The name we use today came later, and to honor its discoverer. In 1919, Castellani and Chalmers proposed renaming the organism Escherichia coli after Escherich. (Along the way it was also briefly classified as Bacillus coli.) The name Escherichia coli was not officially recognized until 1958. So the organism was discovered in 1885 but did not formally carry Escherich's name until seventy-three years later.

Why E. coli was an important discovery

At the time, Escherich's find mattered for understanding the infant gut and digestion. But its real significance came later. Because E. coli is easy to grow, harmless in its common laboratory strains, and simple to work with, it became the organism scientists reached for whenever they wanted to understand how life works at the molecular level. Much of what we know about DNA, genes, and how cells function was first worked out in E. coli. The next section shows just how far that went.

E. coli: the organism behind a record number of Nobel Prizes

E. coli is the preferred model organism in biology because it is easy to grow and work with in the laboratory. It also supports the growth of bacterial viruses (bacteriophages), which made it possible to study the structure and replication of viruses. The process of conjugation, one way bacteria share genes, was discovered in E. coli in 1946 by Joshua Lederberg and Edward Tatum. With its DNA sequence known and its biochemistry studied in enormous depth, E. coli became the organism of choice for biochemists, molecular biologists, and virologists alike.

Because so many fundamental discoveries were made using it, E. coli has been central to an extraordinary number of Nobel Prizes. Below are landmark Nobel-winning discoveries in which E. coli served as the key research organism or tool:

For the full list of Nobel Prizes across microbiology and immunology, see our companion article on Nobel Prizes in microbiology and immunology.

References

• Shulman ST, Friedmann HC, Sims RH. Theodor Escherich: the first pediatric infectious diseases physician? Clin Infect Dis. 2007;45(8):1025-1029. doi:10.1086/521946
• Friedmann HC. Escherich and Escherichia. EcoSal Plus. 2014. doi:10.1128/ecosalplus.ESP-0025-2013
• Etymologia: Escherichia coli. Emerg Infect Dis. 2015;21(8):1310. doi:10.3201/eid2108.ET2108
• FAQ: E. coli: Good, Bad, & Deadly. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK562895/