My girlfriend was always complaining that my yeast storage was taking up a whole shelf in the refrigerator. I have a bin full of Wyeast packs and about 20 slant tubes of yeast strains, including several of the "Private Collection" strains from past availability. She gave me a spare mini-fridge she had in her garage, so I moved everything into the basement the weekend before last and basically forgot about it until last Friday when I was going to get a starter going. I opened the door and reached in pulled out a pack of Wyeast 1581, the PC Belgian Stout and it was frozen solid. I quickly checked the rest and everything was frozen. Even most of the agar in the slant tubes appeared crystallized. The thermostat was set a little past 2/3 cold, so I backed it off and took everything out to thaw.
Fortunately, my LHBS had one each of the PC packs left, so I was able to pick those up and get a starter going. However, I figured I might as well try a starter with the(now thawed) frozen pack as well just to test viability. Unfortunately, no sign of action at all, which is what I was afraid of. So, I decided to make a test starter from one of the slant tubes as well. I figured since they weren't actually immersed in liquid, they may have only frozen at the surface. Sure enough, it took off no problem and I was able to step it up several times successfully.
So, I'm optimistic that I haven't really lost anything irreplaceable, just some frozen packs of the general strains. My best guess is the agar provided some freeze buffer for the cells against it. Obviously, I don't know if all the slants will be as successful, but I'm hopeful that they will be. I have several beers in various stages of fermentation, so I'm able to harvest from those fermenters if need be as well.
So, just an FYI to any potential yeast bankers: Don't freak out if you accidentally freeze a slant tube. You may have some viable yeast yet!
Fortunately, my LHBS had one each of the PC packs left, so I was able to pick those up and get a starter going. However, I figured I might as well try a starter with the(now thawed) frozen pack as well just to test viability. Unfortunately, no sign of action at all, which is what I was afraid of. So, I decided to make a test starter from one of the slant tubes as well. I figured since they weren't actually immersed in liquid, they may have only frozen at the surface. Sure enough, it took off no problem and I was able to step it up several times successfully.
So, I'm optimistic that I haven't really lost anything irreplaceable, just some frozen packs of the general strains. My best guess is the agar provided some freeze buffer for the cells against it. Obviously, I don't know if all the slants will be as successful, but I'm hopeful that they will be. I have several beers in various stages of fermentation, so I'm able to harvest from those fermenters if need be as well.
So, just an FYI to any potential yeast bankers: Don't freak out if you accidentally freeze a slant tube. You may have some viable yeast yet!
