This is for an enzyme, not bacteria, but to answer your question bacteria still need water, so if you keep the plastic dry it should be fine even in such a worl

This is for an enzyme, not bacteria, but to answer your question bacteria still need water, so if you keep the plastic dry it should be fine even in such a world. PET soda bottles will be sterilized, then sealed. The outside is dry and won't decompose. You won't be able to re-close it and leave it out though. For things that need to stay wet, like drain pipes, you would add chlorine and use PVC which is unlikely to be edible to bacteria.