General Category > Yeast and Fermentation

Water in yeast plates?

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boulderbrewer:
Can water in yeast plates (after they are pressure cooked) cause problems, such as yeast showing up where you have not streaked yeast or a crystalization on the edges of the plate?

Kaiser:
Yes, the water can cause the problems you mentioned. I think the water in my plates evaporates slowly through the masking tape I'm using to seal them. After a few days of storage the condensation that was in them is gone.

Kai

boulderbrewer:
Kai,

How do you store your plates upside down? Do you seal them (in a ziploc) or do you just use tape to keep the two pieces together? Just trying to get a grasp on this. Is the cystalization bad if you have not opened the plate?  Can the yeast migrate on the liquid an can you have a viable colony away from the streak.

Kaiser:
I thought I had a picture of this on-line but I don't.

I use one strip of masking tape to hold the two plates together and then another strip that I tape around the bottom edge such that about 2/3 of its width stand over. I then fold that into the center which "seals" the plate. The plates are stores a plastic shoe box where they'll keep for a few month.

I don't use plates for long term storage though. Just to isolate cultures that I then streak onto a slant and/or stab in agar to make a stab culture. Plates get to easily infected due to the large exposed area when I open them.

Kai

roffenburger:

--- Quote from: boulderbrewer on November 23, 2009, 08:42:52 PM ---Can water in yeast plates (after they are pressure cooked) cause problems, such as yeast showing up where you have not streaked yeast or a crystalization on the edges of the plate?

--- End quote ---

I don't see the condensation causing a problem unless its excessive. How much condensation are we talking about? You shouldn't have a puddle. If the condensation gets on the media after you streak, it can swirl around in the plate and "run." Its not a big deal. Store your plates media side up for a day or two and the condensation will evaporate some and be absorbed by the media some. This is the proper way to store (storage and incubation) plates as it prevents them from drying.  You can also open your plates, and dump the condensation (if its really bad), holding the plate in a manner that minimizes the chance of contamination--hold the media so that it faces down. Its not really necessary to tape them shut unless storing them for a while, though it won't hurt and it might be a good idea if you're clumsy ;). I would personally store in a bag instead of taping shut.

Just keep in mind that the kitchen is not a clean place. Use good aseptic technique and you'll be fine.

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