ABSTRACT
The human gastrointestinal tract contains a complex ecosystem of microorganisms with more than 400 different bacterial species, and potentially thousands of different strains. These bacteria are highly important to our health. They provide us with a barrier to infection by exogenous bacteria (1) and much of the metabolic fuel for our colonic epithelial cells (2) and contribute to normal immune function (3). Disturbances to this ecosystem leave us more vulnerable to exogenous and endogenous intestinal infections. Intestinal bacteria have also been implicated in causation of some chronic diseases of the gut such as Crohn’s disease and ulcerative colitis (4, 5). As we age, changes occur in the composition of the intestinal microbiota that may contribute to an increased level of undesirable microbial metabolic activity and subsequent degenerative diseases of the intestinal tract (6, 7). Manipulating the intestinal microbiota to restore or maintain a beneficial population of microorganisms is a reasonable approach to maintaining intestinal health in cases when a deleterious or less than optimal population of microorganisms has colonized the gut.
