I'd like to also add another bit of interest since you wanted to "know more". Proof in someways on how important gut bacteria is to our overall health. There exists a treatment for people with intestinal issues which, summed up, is essentially a poop transplant. They take some from a very healthy person and seed your gut with it. All that healthy bacteria take hold and suddenly you are functioning significantly better.

(First link i found, in sure theres better ones) https://www.puretyclinic.com/fecal-transplant-fmt-santa-barbara