ABSTRACT
The human gastrointestinal tract is home to myriad microorganisms actively metabolizing food residues, physiological secretions and cell debris in the luminal contents. Their activities may be beneficial, detrimental or of no account to the host. In order to unravel the different mechanisms that maintain the balanced ecosystem within the gut, and to determine their effects on the host, it is necessary to resort to an animal model in which the gastrointestinal flora can be controlled.
