DH5a vs XL1Blue

[Rudi van de Wetering]

> Xl1-Blue is a LacIq strain (and requires tetracycline for selection of the
> F'), whereas DH5alpha is not. That means that XL1-blue overexpresses the
> lacI protein, and thus represses the lacZalpha gene on plasmids like pUC19
> much better than Dh5alpha.

Thougth you also had to add Maltose for selection/expression of the F'  (at
least if you use LB). And that the F' is only important if you're gonna
infect them with a bacteriophage. Anyway, that is the only thing i use
XL-blue for.