Fig. 1

The bacterial flora inhabits in regions of human gastrointestinal tract constitute a complex ecosystem. More than 10 [14] microorganisms, 500 bacteria species have been identified in GI. The upper gastrointestinal tract (stomach, duodenum, jejunum, and upper ileum) is usually contained Lactobacillus, with bacterial concentrations less than 10 [4] microorganisms/ml. By contrast, bacteria in the large intestine are dramatic increase as 10 million bacteria. Anaerobic bacteria (A. bacteria) such as Bacteroides, Enterobacter, Anaerobic Streptococcus (A. Streptococcus), Clostridium and Lactobacillus are 1000 times more abundant than facultative anaerobes such as E. coli. It is a general trend that bacteria increase in complexity and concentration as they enter the gastrointestinal tract