Escherichia coli is an Enterobacteria described by [see Bergey's Manual (1957)]. Escherichia is a Gram-negative rod which can be motile by peritrichous flagella or nonmotile. Escherichia is also a facultative anaerobe which has both a respiratory and a fermentative type of metabolism, and commonly occurs in the intestinal tract of humans and other animals. The strain E. coli K-12 is a debilitated strain which does not normally colonize the human intestine. It has also been shown to survive poorly in the environment, has a history of safe commercial use, and is not known to have adverse effects on microorganisms or plants.
Because of its wide use as a model organism in research in microbial genetics and physiology, and its use in industrial applications, E. coli K-12 is one of the most extensively studied microorganisms. As a result, these K-12 strains are well-characterized and should be expected to remain as pure cultures under standard microbiological practices. K-12 strains are distinguishable from other Escherichia.
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