The fastest way that bacteria adapt is usually by horizontal gene transfer. They can mutate very quickly by comparison to Eukaryotes but it’s much harder to invent new metabolic pathways or systems that way rather than sucking them in from the vast global metagenome pool.
Those in your e-coli-ological niche, yes.
What if the virus-proof bacteria mutate and take over other niches? Can’t bacteria mutate very quickly?
The fastest way that bacteria adapt is usually by horizontal gene transfer. They can mutate very quickly by comparison to Eukaryotes but it’s much harder to invent new metabolic pathways or systems that way rather than sucking them in from the vast global metagenome pool.