Phage library contamination

Matthias Zeiner mzei at
Tue Apr 26 07:17:35 EST 1994

Recently I read in Paul Hengen's column in TIBS about contaminated 
libraries sold by Clontech (TIBS 18,Dec.93, TIBS 19,Mar.94).
I had the very same problem with a lambda gt11 human liver cDNA library 
from Clontech some time ago: very large plaques appeared after only a 
few hours. When I complained Clontech gave me a refund (in return I 
purchased their "5'Amplifinder RACE kit" which didn't work at all..... , 
but that's another story). 
The contaminating phages in my library were not T1 but probably T7 as they 
were not very infective and showed a typical plaque morphology.
Interestingly the large plaques only appeared when I plated the library on 
Y1090 strains from other suppliers than Clontech, although these strains 
were not contaminated by themselves. Using Clontech's Y1090 strain, only 
lambda phages and no T7 showed up. 
These are my conclusions:
1) Clontech have well been aware of their contamination problem.
2) With their gt11 libraries Clontech supply Y1090 strains that are    
   resistant to T7. Probably they harbor a F'plasmid providing       
3) Since only few people notice that problem Clontech don't think 
   it's necessary to inform the public.
   I doubt, that this kind of information policy is adequate in the    
   field of scientific research.

Matthias Zeiner
Institut f!r Biologische Chemie
INF 501
D-69120 Heidelberg
mzei at

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