Where did these new bacteria come from, and why are they on the ISS?

Humans are filthy. No, I don't mean we bring garbage with us wherever we go, though we tend to do that as well, we're really just filthy creatures. We're covered in bacteria inside and out, but that's not a bad thing. The vast majority of bacteria on and inside of our bodies are beneficial and actually keep us alive and healthy. In fact, we bring so many different kinds of bacteria with us wherever we go that scientists are still finding new ones they've never seen before. That appears to be wha...