The surface of the human gut has a surplus area of 200-250 m2 in order to contain, between intraepithelial lymphocytes and lamina propria, Peyer’s patches and lymphoid follicles, the lymphoid tissue, while hosts a flora of about 800 different bacteria species with over 7000 strains. The 99% are obligate anaerobes and varies species were then classified using traditional anaerobic culture techniques. More than 50% of the dominant gut microbiota (corresponding to 10 8-10 11 per gram of faeces) cannot be identified using traditional colture ,but molecular approaches, based on the use of 165 ribosomal DNA molecular (Mai & Morris, 2004). Most of these bacteria colonizes the large.
