The term microbiota is used to describe the complete population of microorganisms that
populate a certain location, such as the gut, and is preferred to the term flora as the former
incorporates not just bacteria but also archaea, viruses, and other microorganisms, such as
protozoa. Though the potential role of the microbiota (through such concepts as “the
putrefactive principle associated with faeces” and “intestinal toxins”) in the pathogenesis of
systemic disorders has been recognized since antiquity, a firm scientific basis for a role for …