Escherichia coli (E. coli) is a rod-shaped bacterium that lives in the gut of warm-blooded animals. It is a crucial tool in modern biotechnology and often used in molecular biology laboratories due to its ease of culture and rapid growth. Scientists use E. coli to work with DNA and proteins from other organisms. It is a normally harmless bacteria that lives in the lower intestine though some strains of this bacterium can cause infection of the intestine, urinary tract and other parts of the body.