I am using competent, commercially bought DH5a to obtain plasmids of interest. I understand that chemical treatment with CaCl2 or whatever other method used induces competency on treated bacteria and is not a genetic trait by any means; so it cannot be "inherited" by simple division. Treated bacteria (especially if bought) should be viable or else it wouldn't work when trying to grow and select transformed bacteria. I understand that when bacteria reproduce by division, part of the old membrane is "given" to both of the resulting cells, so perhaps the competency should be less but not gone; although through multiple division there would end up being bacterias that just aren't competent. That shouldn't be a problem though, as bacteria conjugate and pass plasmids to one another.
My lab mate doesn't understand why competent bacteria don't produce more competent bacteria, and instead produce non competent bacteria that must be treated with CaCl2 again. Perhaps it isn't the way I just explained it? or maybe he just doesn't understand me.
Also, I would like to know: in theory, if I were to grow DH5a just to mantain a permanent stock of them without buying them again, should it be possible?
Thank you very much in advance.
Basically, the chemical comptetency is caused by moderate damage to the cell wall & membrane of the bacteria. That damage is repaired when the bacteria are cultured - it does not persist long in culture, or once the bacterial become metabolically active again. This is part of why you want to perform a transformation rapidly once the competent bacteria are thawed.
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