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minor problem preparing plates

Galo Ortiz/WebDeveloper appliedc at worldnet.att.net
Wed Jun 18 10:38:22 EST 1997

Michael Stockelman wrote:
> Hi, all!
>         I am a new worker in yeast and I just had a small problem while
> preparing some YPD plates.  In about the time it took for the plates to
> cool on my bench after being dispensed, they pretty much all developed a
> scattered covering of liquid droplets.  I put the plates in plastic
> sleeves overnight in the fridge, then used them today.  The droplets were
> gone (dried? absorbed?) but the plate surfaces now had bumps all over
> where the droplets had been.  When I spread liquid on the plates the bumps
> quickly dissolved, so they are soluble deposits (not deformation of the
> agar).  This has never happened for me with bacterial plates.  Why did my
> plates turn out this way? How can I avoid it?
> Thanks,
> Mike Stockelman

It seems to me that condensation is your main problem. After autocalving
the the YPD let it cool for as long as possible (to avoid condensation)
and then pour the plates. Let the plates solidify at room temperature
(usually for 24hrs.) and then bag them and place in the refrigerator.
When you bag them place them up-side down (with the cover on bottom). If
you find water drops on the cover when you're about to use them, grab
the plate with one hand (still upside down) and quickly take the cover
off and shake the water drops off and place the cover back on it. While
I know this is no the most sterile way to do things contamination was
never a problem.

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