Figure 2.
The main taxa of bacteria in the gastro-intestinal tract (over genera 500, and 1012–1014 microorganisms). The stomach carries about 102–103 bacteria, the duodenum 104–105, the ileum 108–109, and the bacteria and colon 1013–1014 (per gram of tissue or feces). Larger numbers of bacterial cells have been found in the large intestine, with 1012 bacteria (per gram of intestinal tissue), and the variety of bacteria is greater than that in the small intestine [1,6]. According to a hypothesis for the prevalence of genera in the human microbiota, there can be three main enterotypes, which are Bacteroides (enterotype 1), Prevotella (enterotype 2), and Ruminococcus (enterotype 3) Credits: Original figure by I.A. Charitos.