Comment by ACCount37

We're talking removing all bacteria. And we know it's possible - even if it can't happen in nature.

There are sterile mice made for scientific uses - 100% mouse, completely microorganism free or your money back. They have health issues, but they can survive and reproduce in the right conditions.

Of course, those "right conditions" include sterile housings and sterilized food, because they'll get contaminated otherwise.