Facultative anaerobic bacteria Gram-negative

Escherichia coli is a member of the bacterial family, Enterobacteriaceae, the enteric bacteria. Members of the Enterobacteriaceae are among the most important bacteria medically. A number of genera within the family are human intestinal pathogens (e.g., Salmonella, Shigella, Yersinia). Several others are normal colonists of the human gastrointestinal tract (e.g., Escherichia, Enterobacter, Klebsiella), but these bacteria, as well, may occasionally be associated with diseases of humans. E. coli is a facultative anaerobic, motile, gram-negative rod. 

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