beta-ME in transformations?

Tara McCready tara_mccready at
Fri Jul 7 15:38:44 EST 1995

Stratagene recommends using 25mM beta-mercaptoethanol in transformations
of their competent TOPP strains (as well as XL1-Blue, JM109 and others). 
They state that it has been shown to increase transformation efficiencies
2-3 fold.  Their protocol involves incubating thawed cells in BME for 10
minutes on ice before addition of DNA.   Can anyone tell me how this
increases transformation efficiency?  In my hands it appears to reduce the
number of transformants, if anything.

Thanks ,

Tara McCready
Dept of Biochemistry
University of Alberta
Tara_McCready at

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