Escherichia coli

Escherichia coli (/ˌɛʃᵻˈrɪkiə ˈkoʊlaɪ/; also known as E. coli) is a Gram-negative, facultatively anaerobic, rod-shaped bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in their hosts, and are occasionally responsible for product recalls due to food contamination. The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K₂, and preventing colonization of the intestine with pathogenic bacteria.E. coli is expelled into the environment within fecal matter. The bacterium grows massively in fresh fecal matter under aerobic conditions for 3 days, but its numbers decline slowly afterwards.

E. coli and other facultative anaerobes constitute about 0.1% of gut flora, and fecal–oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for a limited amount of time, which makes them potential indicator organisms to test environmental samples for fecal contamination. A growing body of research, though, has examined environmentally persistent E. coli which can survive for extended periods outside of a host.

Escherichia coli (molecular biology)

Escherichia coli (/ˌɛʃᵻˈrɪkiə ˈkoʊlaɪ/; commonly abbreviated E. coli) is a gammaproteobacterium commonly found in the lower intestine of warm-blooded organisms (endotherms). The descendants of two isolates, K-12 and B strain, are used routinely in molecular biology as both a tool and a model organism.

Diversity of Escherichia coli

Escherichia coli is one of the most diverse bacterial species with several pathogenic strains with different symptoms and with only 20% of the genome common to all strains. Furthermore, from the evolutionary point of view, the members of genus Shigella (dysenteriae, flexneri, boydii, sonnei) are actually E. coli strains "in disguise" (i.e. E. coli is paraphyletic to the genus).

History

In 1885, Theodor Escherich, a German pediatrician, first discovered this species in the feces of healthly individuals and called it Bacterium coli commune due to the fact it is found in the colon and early classifications of Prokaryotes placed these in a handful of genera based on their shape and motility (at that time Ernst Haeckel's classification of Bacteria in the kingdom Monera was in place).