Introduction .Molecular Ecology of the Human Intestinal Microbiota.Sampling Microbiota in the Human Gastrointestinal Tract.The Normal Microbiota of the Human Gastrointestinal Tract: History, Succession and Dietary Influence.The Intestinal Microbiota of Elderly.Immune Modulation by the Intestinal Microbiota.Mucosal Interactions and the Gastrointestinal Microbiota. The Metabolism of Nutrients and Drugs by the Intestinal Microbiota. The Metabolism of Polyphenols by the Human Gut Microbiota. Molecular Analysis of Host-Microbe Interactions in the Gastrointestinal Tract. The Infant Intestinal Microbiota in Allergy. Probiotics: A Role in Therapy for Inflammatory Bowel Disease? The Gastrointestinal Microbiota in Cancer. In Vitro Methods to Model the Gastrointestinal Tract. Animal Models for the Human Gastrointestinal Tract. Born Germfree - Microbial dependent. Modifying the Intestinal Microbiota: Prebiotics. Modifying the Intestinal Microbiota with Probiotics. Modifying the Intestinal Microbiota with Antibiotics. The Intestinal Microbiota of Pets; Dogs and Cats. The Gastrointestinal Microbiota of Farm Animals. Perspectives.