Characters will not be passed to next generation as variations are produced.am I right?

It's pretty much impossible to get rid of bacteria, especially since it reproduces at unstoppable rates. It exists in many forms and some is harmless which makes it difficult to determine. So, after 100 years, the bacteria would regenerate into new forms of the original bacteria, although the original would still exist. You can take the common cold(form of bacteria) for example. It has existed for thousands of years and still does.
Even if the earth was to be destroyed by a nuclear wepaon, bacteria could still exist. Even if human and animal life went extinct.