Hanahan competent E.coli

LOGAND logand at msdos.montpellier.inra.fr
Wed Apr 19 04:57:36 EST 1995


I am planning to prepare competent cells by the Hanahan method to use for 
the transformation of many ligation reactions (nested deletions prepared 
using the Pharmacia kit). I have never used this transformation protocol 
before, Sambrook et al. states that the number of cells in the culture 
should not exceed 1x10^8/ml and one should determine the relationship 
between OD and viable cell number/ml for the strain to be used. Well, I 
would love to be able to omit (or at least limit) this time consumming step 
- thus, can anyone give me a value for this using DH5a? I realise I will 
have to check/re-calculate this due to differences in spectrophotometers 
(light scattering etc) but at least I would have an approx. starting point.

Finally, do XL1 blue cells give worse or better transformation frequencies?


David C. Logan

Logand at montpellier.inra.fr 

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