ABSTRACT
Identifying the components of the gut flora and investigating their biochemical activities has occupied the mind of microbiologists from the very earliest days of this branch of science. This chapter provides an overview of the components of the gut flora at different sites within the gastrointestinal tract in health and disease. In order to interpret correctly the qualitative and quantitative data generated from studies on the flora of the gastrointestinal tract it is important to be aware of the limitations imposed on such studies. The major problems are those of the extreme complexity of the ecosystem under investigation and the inaccessibility of many parts of that ecosystem in a healthy subject. The difficulties that may influence the results fall into two major groups, sampling transport and storage, and cultivation, enumeration, and identification.
