While preparing E. coli DH5alpha competent cells, most of the methods describe using E. coli DH5a at OD 0.4-0.5. Is there any specific reason for using OD 0.4-0.5? If OD is more than 1, will it be an issue for transformation?
Thanks
There were many studies done on optimizing transformation efficiency and virtually all concluded that logarithmically growing cells were best. When you get to OD of 1 range the cells are already hitting saturation (depending upon aeration conditions etc). They will still work but efficiency will probably be reduced.
Dear Abdullah Al Tarique
the idea is stop the culture when the cells are joung and with the best viabilitiy. in LB or similat media, at OD>0.8-1 you are no so far from the maximun O.D, the oxigenation level decrease and also the cell viability, therefore you risk to obtain an higher number of cells but with less compatency and viability which will not improve your trasformation efficiency.
good luck
Manuele
If you havedifficulties in achieving the desired optical density (OD), the following protocol is recommended:
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