Which of the following is non-pathogenic bacteria of colon?

Escherichia coli is the non-pathogenic bacteria of colon. One of the characterisites of Escherichia coli is the production of bacteriocins (colieins), a specific type of metabolite which is not only lethal to the organism of the same species but also to related organisms. Balantidium coli results in inflammation of alimentary tract. Entamoeba coli causes amoebic dysentery. Enterobius vermicularis infection is known as oxyuriasis or enterobiosis.