What mechanism allows both bacteria and viruses to survive harsh environments e.g in the gut?

I'm guess is that... the bacteria and viruses forma a thick coat, called an endospore inside them that allows them to survive harsh enviorments while making them dormant (resting cells) at the same time. once the envorment becomes suitable again, the endospore deteriorates and thus the bacteria or virus once again becomes prominant ( non- resting, it can move around now).

i think soooooooooo