@freemo Yeah, I've long had some questions about this myself. I remember that movie when it came out.
Our digestive system is entirely dependent on the microbes that live in our gut. Our mouth and stomach add enzymes and acid, and mix it up to get the process moving. But the heavy lifting is done by our gut microbiome. We can't survive without it. So I've always been puzzled about the sterile environment thing. Maybe they're not counting gut bacteria as pathogens?
I'm an engineer. Maybe the answer is obvious to a microbiologist.
@shuttersparks it doesnt add up to me because I know that gut bacteria, out of blaance, can become dangerous (though that is rare)... so I dunno.