The colonic microbial community is the most densely packed, metabolically active, and best-studied due to the ease of stool sample collection.

“And then you get to the colon, and this is the community that's just so incredibly densely packed, doing a ton of... There's a ton of metabolic activity happening there, and a bunch of interaction with the host. And that's the community that's really the best studied. Part of the reason for that is because stool is so easy to obtain compared to, for instance, something in the stomach or small intestine. And that stool is fairly representative, we know, from studies that have been done using colonoscopies and so forth. Stool is fairly representative of what's happening in the colon.”