E. coli strain for plasmid prep AND expression

[vernet]

I am looking for an E. coli strain for efficient transformation (recA) AND good expression of gene under lac promotor that can also deliver good quality plasmids. Any hints?

[biostudent84]

Usually, you can kill off all bacteria that are NOT part of your experiment. You might have one or two left, but let them divide a few times, and you can quickly come up with a good culture.