Can you show me bacteria that's been around from the beginning, if they don't die we should have bacteria that are millions of years old according evolutionary timescales.
As long as conditions are right, bacteria will grow and then divide once they reach a certain size. Once one bacteria has divided into two, are these two new bacteria; or are both or one the same as the original bacteria? If the latter, then every bacteria, and every other living cell, is thousands of millions of years old. All living cells arose from division of a previous living cell, and so each traces a continual existence since the earliest beginnings of life without ever dying.
When conditions aren't right for cell growth and division, one of two things can happen. If something in the environment irreperably damages the cell, then it will die - as its parts are no longer connected in the correct way for life to be maintained. In the right conditions though, growth will stop but the cell will not die, and will happily go back to growing and reproducing once conditions are right again - even if this is millions of years later.
It's not a bacteria, but
here's an example of an even more complex organism, eukaryotic yeast cells, which were revived after 45 million years and then used to make beer! These cells had been lying dormant for a long time, but because nothing irreparably disrupted the organisation of the cell, they can still get on with things when conditions are right.
The same research team* has gotten even more impressive results with dormant bacteria, claiming to have revived strains which have lain dormant for
up to 250 million years.
There really are bacteria millions of years old, whichever way you look at it.
*ABE - sorry, I misread. It wasn't the same research team, it was another from West Chester University.
Edited by caffeine, : typo
Edited by caffeine, : ABE footnote