If I take a frozen glycerol stock out of the freezer, can I leave to to defrost then immediately place it into the inoculating broth as my started culture and incubate it thereafter? I do not first want to streak the cells out, as the agar may contain contaminants; I want to avoid this, altogether.
7/1/21
Dear Danielle,
If your yeast culture is pure (i.e., no contamination by other microbes) and it was stored frozen in a sterile vial, you should be able to transfer it directly to your inoculating broth. The freeze/thaw process will kill some of the yeast, but enough will survive to function as an inoculum.
If you want to streak the yeast out on agar just to be sure the cells are viable and the culture is pure, you can do so. It will cost you a day or two in time, but that's a minor problem. I don't understand your comment about the agar containing contaminants. If the agar is prepared and autoclaved properly, it will be sterile (i.e., uncontaminated).
I hope this information helps you.
Bill Colonna Ames, Iowa, USA [email protected]
Dear W.J. Colonna
Thank you very much for your assistance. This is what I had in mind, however, some literature pieces stated that it is not correct to thaw the stocks out completely. So thank you for the clarification :)
Hi Danielle,
I'm agreeing with W.J. Colonna's response. Literature might not be stated clearly for the procedures. In my usual practice on bacteria or yeast culture, the freeze/thaw process will kill the cell over time, and an increase in temperature will affect the stability of the expressed protein. So, if you're not planning to use it as soon as it defrosts, you might need an icebox or cooling rack to store your glycerol stock so that it can preserve the stock for a longer period of time.
Hope this helps!
Chloe
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