Escherichia
Escherichia is a genus of Gram-negative, rod-shaped bacteria in the family Enterobacteriaceae. Members are typically facultatively anaerobic and may be motile with peritrichous flagella, though some species are non-motile. The genus contains numerous species, of which the best known is Escherichia coli (E. coli), a normal inhabitant of the intestinal microbiota of humans and warm-blooded animals and a frequent cause of disease when displaced. The genus lies within the Gammaproteobacteria, order Enterobacterales, class Gammaproteobacteria, phylum Proteobacteria.
Most Escherichia species are commensals in the intestinal tract; some environmental species are found in water
In the laboratory, E. coli strains such as K-12 are widely used as model organisms and vectors