system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are bacteria created?

Just read a news article about how 3 completely new types of bacteria have been found on the international space station due to it's isolation, if that's the case then how did they get there if we have never observed them before? what created them?
gpt
Some similar bacteria likely travelled up there on the astronauts or some item. 

What makes every organism unique is it’s DNA. bacteria change their DNA a lot, it’s why they adapt so fast. If they make a change that makes them unable to survive, those DNA changes will not be passed on. What determines if the DNA changes are good or bad is the environment. 

For instance, if some change makes you better at surviving in the cold, but you live in a hot climate, it likely won’t get passed on. In a cold climate, it could be very useful. 

The ISS is a very unique environment. Everything is precisely controlled and does not exchange anything with the outside. This would lead to unique DNA changes being passed on. 

A similar situation is observed on islands. Before people started moving around so much, taking animals and diseases with them, islands bred unique organisms because they were isolated from each other.