Although E. coli has been often in the news as a foodborne pathogen, the vast majority of E. coli strains are harmless, including those commonly used by scientists in genetics laboratories. E. coli is found in the family of bacteria named Enterobacteriaceae, which is informally referred to as the enteric bacteria. Other enteric bacteria are the Salmonella bacteria (also a very large family, with many different members), Klebsiella pneumoniae, and Shigella, which many researchers consider to be part of the E. coli family.
E. coli bacteria were discovered in the human colon in 1885 by German bacteriologist Theodor Escherich. Dr. Escherich also showed that certain strains of the bacteria were responsible for infant diarrhea and gastroenteritis – an important public health discovery. Although the bacteria were initially called Bacterium coli, the name was later changed to Escherichia coli to honor its discoverer.
Soon after its discovery, E. coli became a very popular lab organism because scientists could grow it quickly on both simple and complex mediums. E. coli can grow in air, using oxygen as a terminal electron acceptor (aerobically) or without air, by what is called fermentative metabolism (aerobically). The ability to grow both aerobically and anaerobically classifies the E. coli bacteria as a facultative anaerobe.