Yeast two hybrid contamination

Frederik Boernke boernke at
Tue Mar 10 16:57:13 EST 1998

Matt Benson wrote:
> Hi,
> I've now done about 4 yeast 2-hybrid screens and every time after 5 days
> incubation at 30C am getting small, brownish, glassy colonies which
> absolutely stink.  (And no positives!) These look nothing like my yeast,
> I've checked out my bait strain extensively for self activation and using a
> known interactor (which worked perfectly ), each screen has used fresh media
> and colony PCR on the small, smelly colonies show that they do not contain a
> prey plasmid.  I'm using a mouse brain cDNA library from Origene with the
> Hybrid Hunter system from Invitrogen.  Two of the screens have been
> performed with the Gietz method and two with the Clontech manual variation.
> I am now getting very frustrated!
> Any ideas greatly appreciated
> Cheers
> Matt

Hi Matt,

I found the waterbath to heat shock the cells during transformation 
being a source of contaminations, also drying the plates under the
laminar with leaving the lids open can cause growth of some nasty little
Just a thought,



Frederik Boernke
Research Group of  Molecular Plant Physiologie
Institute for Plant Genetics and Crop Plant Research (IPK)
Corrensstr. 3
06466 Gatersleben
Tel.  039482 -5 321
Fax. 039482 -5 515
e-mail: boernke at

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