Gentamicin screening -> blank plates

Michael Deyholos mdeyholo at
Mon Feb 20 10:13:26 EST 1995

Has anyone experienced difficulty while screening transformants for 
Gentamicin resistance?  I am trying to transform XL1-Blue with a pCGN1547 
derived plasmid, but after plating on LB plates with 20ug/ml Gent, I never 
observe any growth.

I realize that there are dozens of trivial explanations for the apparent 
failure of the transformation.  However, I was told that sporadic 
problems with Gentamicin are common...some people seem to vaguely 
remember something about light sensitivity of gent on plates...but they 
can't be sure.

Any further information would be appreciated.


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