arginine biosynthesis-delete (Escherichia coli)

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Escherichia coli (play /ˌɛʃɨˈrɪkiə ˈkoʊlaɪ/;[1] commonly abbreviated E. coli) is a Gram-negative, rod-shaped bacterium 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 humans, and are occasionally responsible for people making product recalls.[2][3] The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2,[4] and by preventing the establishment of pathogenic bacteria within the intestine.[5][6]

E. coli and related bacteria constitute about 0.1% of gut flora,[7] 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 ideal indicator organisms to test environmental samples for fecal contamination.[8][9] There is, however, a growing body of research that has examined environmentally persistent E. coli which can survive for extended periods of time outside of the host.[10] The bacterium can also be grown easily and inexpensively in a laboratory setting, and has been intensively investigated for over 60 years. E. coli is the most widely studied prokaryotic model organism,[citation needed] and an important species in the fields of biotechnology and microbiology, where it has served as the host organism for the majority of work with recombinant DNA.