Figure 2.

Longitudinal differences along human gastrointestinal (GI) tract

(A) The abundance of key taxa in a specific gut area, as averaged across all individuals tested in a given study. Six studies are included based on the requirement that they investigated different gut regions within specific individuals. Despite the differences in sampling and microbial analysis techniques, this revealed the consistent difference between microbial communities of the upper and lower GI tract. One community colonizes the duodenum down to the proximal ileum (generally dominated by Pseudomonadota, Streptococcaceae, and Veillonellaceae) and one colonizes the distal ileum down to the rectum (generally dominated by Bacteroidaceae, Lachnospiraceae, and Ruminococcaceae).

(B) Weighted average of all the studies included in (A).