Good afternoon everyone, I have a question as a beginer in this field. I'm running out of a plasmid that is very important for my research project, that's why I'm planning to insert it in a bacteria to get more copies of it. I have these competent bacteria on my lab: BL21(DE3), 5-alpha, 10-beta and DH10B. As I know, BL21 is for expression, but which of the other ones can give me more copies of my plasmid?
Thank you very much.
Short answer: Most of those strains would work.
I would generally recommend using DH5α or DC10B. DH5α is my preferred strain as it is deficient in recA (so your plasmid doesn't do funny things with recombination) and endA/hsdR deficient (so your plasmid is less likely to be chewed up by endonucleases). Typically this strain is used for chemical/"heat shock" transformation (which is generally quicker and cheaper if you're making your own competent cells). In theory DH5α can degrade methylated DNA but we have not observed this as a problem in DH5α.
A good alternative strain is DH10B. It is very similar to DH5α but has additional mutations so that it is even less capable of degrading foreign methylated DNA. In my experience, DH10B is typically made electrocompetent and used for electroporation.
The last thing you should consider is which origin of replication your plasmids are using. Some of the more specialized ones require pirA expression for efficient plasmid replication and maintenance. Other considerations include the size/recombination potential of the insert and whether you want the DNA recovered from your E. coli strain to have specific methylation patterns (which can be important for downstream applications/transformations)
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