Growing Wyeast Strains in Selective Media

Does anyone know what selective media Wyeast Labs uses to grow their strains? For example, maybe the American Ale 1056 strain is URA-. I'm sure not all are the same and it's a fairly easy experiment to do, but I'd figure ask here to see if anyone knows or has done this before I invest the time into my favorites.

Thanks.

Not sure exactly what you mean, in their commercial labs they will use a number of selective media to control various characteristics. In a home setting, Malt Agar is the usual choice, but Potato Dextrose Agar can alse be used.
If you can explain what you are trying to do a bit more clearly, it might be easier to help, but from what you say, it sounds like you are trying to hard to do something that Wyeast can do far cheaper and more reliably. Trust the professionals.

They wouldnt use selective mediw, thesr are essentially pure strains with no selective markers. They just make extra super certain everything is sterile, grow yeast up in conditions similar to the beers they're meant for and keep the numbers of generations to aminimum. That's it as far as i know.

Thanks for the replies. I was essentially trying to keep potential contamination down by using selective media. I just want to store and reuse a few strains I use a lot.

daksin - Thanks. That's interesting that they don't use any sort of selection.

bluedubbed said:

Thanks for the replies. I was essentially trying to keep potential contamination down by using selective media. I just want to store and reuse a few strains I use a lot.

daksin - Thanks. That's interesting that they don't use any sort of selection.

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In the lab we use positive selection like nutrient markers, but in a food lab, they're not going to want to alter the yeast (and by extension, the beers) by changing the way the yeast metabolize different nutrients.

Also, yeast aren't like bacteria where you can use antibiotic/antimycotic plasmids to generate negative selection conditions- can you imagine the problems associated with introducing yeast that manufacture antibiotics into beers? There's enough allergy problems with beer as it is!

I suspect (this isn't confirmed- I don't work for a food lab like White or Wyeast) that they just have extremely pure Stock cultures in a library, grown up from single cells, and they maintain these stocks and grow up production batches from those, maintaining sterility the whole way.