In article ,
Curious wrote:

It would be nice to genetically-engineer some bacteria to feed on our
stools in our colons. That way we would never need to defecate.

Your stools are mainly composed of bacteria and dead intestinal lining
cells, especially if you eat a typical American diet that is low in
fibre and high in protein and refined grains. So they've already fed
on your stools and turned them into more bacteria.

Besides, defecation is good for you. Low fibre diets are strongly
associated with a range of ailments from the merely painful and
embarrassing like hemorrhoids and anal fissures to the life-threatening
like appendicitis and diverticulitis to colon cancer which is usually
fatal unless detected early.