E. coli: Escherichia coli is part of the normal human intestinal flora. E. coli has been studied intensively in genetics and molecular and cell biology because of its availability, its small genome size, its normal lack of pathogenicity (disease-causing ability), and its ease of growth in the laboratory.
Most strains of E. coli are quite harmless. However, some strains of E. coli are capable of causing disease, sometimes disease of deadly proportions.
