[Heartlander]

As shown in “Biological cost of rifampin resistance from the perspective of Staphylococcus aureus”… mutations that confer rifampicin resistance tend to be lost after the antibiotic is removed because the mutations significantly impair the ability of RNA polymerase to do its job.

But more importantly, when the integrity of the ‘genome’ is threatened - life fights back. Why? Is this by design?

[allmendream]

It is not a difficult concept, perhaps you have heard of it, it is called “There is no such thing as a free lunch”.

In biology it is also called antagonistic pleotropy.

What do you mean “the integrity of the genome”?

The genome has functionality, it is not set it stone, but in fact it is INCAPABLE of being reproduced with 100% fidelity. Thus there is, over time, no “integrity” to the genome.

In the case of bacteria, they have a specific gene for an error prone DNA polymerase that they use to reproduce their genome during times of stress instead of the regular high fidelity DNA polymerase?

So if by “fight back” against environmental stress you mean “supercharge evolutionary change by expressing error prone DNA polymerase” then yes.