Long term yeast storage: agar vs. water

[JohnMc]

In cases where strain deterioration occurs (and while it undoubtedly does, I think it is talked about far more often than it is observed) it is, I am fairly certain, almost solely because of contamination.

10-4 on that.
I will say I *think* I've seen some strains throw petites (something wrong with the mitochondria), but I've been too lazy to check them on the right media (0.1% glucose and 2% glycerol, IIRC).
Basically, RDWHAHB.

 

[ni*]

Mitochondrial ejection, specifically. But yes, a petite phenotype is normally induced by dodgy media.

 

[bobz]

How long does a homebrewer need to store yeast. Sterile distilled water will get you < 2 years depending on your procedure. I pressure cook distilled water in 8ml vials and pipette 2-3 ml in each vial every time I smack a pack or open a liquid culture. stores at room temp. 400x is the recommended microscope power.
I do 6 vials every time. -------bobz

 

[JohnMc]

Mitochondrial ejection, specifically. But yes, a petite phenotype is normally induced by dodgy media.

Actually, petites can simply be respiration deficient and the mutations can be nuclear or mitochondrial mutations; the mitochondria can still be present, though generally funked up.

How long does a homebrewer need to store yeast.

That depends. If it's to save money and master the process, not long really. If it's to really preserve strains, then longer. I've had MeV Stout in storage since '92 or '93. MeV went out of business in either the late 80's or early 90's. It's not really needful to have it, good stouts can be made with other yeast. It is nice to have, though, because it's very distinct. All of the Brewtek strains would also be nice to have. I think they went under in 2004 or so.
You can get most of them from the ATCC, but they're $275 each, IIRC. I didn't order them at that price...