Contaminated -Taq

Denis Gaucher dgauch at
Mon Feb 23 03:37:50 EST 1998

brett wrote:
> >Hi,
> >I have been trying to set up a PCR with bacterial DNA .
> >The problem is that my negative(no DNA) controls are showing up positive on a
> >PCR check gel.
> >I have tried changing all reagents and I have tried 6 different Taqs from
> >different manufacturers!! The negative PCRs still come up with a product!
> >Has anyone of you ever had problems with contaminated Taq??
> >If you have what did you do???
> >I am right now convinced that all Taqs are contaminated.
> >Lala
> WOW! Maybe your H2O, primers, or buffer are contaminated, but these seem more
> likely than 6 tubes of Taq from 6 manufacturers. Back to the bench, and better
> tighten your thinking cap.

...or maybe your pipetmen are contaminated with the template... did you
wash them in HCl or use plugged tips?  Did you try to do the PCRs in
another lab with different instruments and totally new solutions? I
agree that the contaminated Taq explanation is not likely....


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