Charlottesville Area Masters of Real Ale

I need some advice on how best to store yeast over the course of a year or more.  I bought some White Labs Australian Ale yeast WLP009 recently.  It is a part of their platinum series that is released on an annual basis in Jan-Feb. However, I'd like to use this strain for a couple batches throughout the coming year.  Rather than reusing the yeast cake from batch to batch, I wanted to grow up some of this strain and set up aliquots that I could pull from time to time.  So I've got a starter size culture growing up now and I've got 2 qts so far.  My plan was to put it in the fridge for a day or so until it flocculates, pour off much of the fermented wort (is there anything I could do with this?), then aliquot the yeast into several sterile 50ml conical tubes with 20% glycerol.  Then whenever I wanted to use this strain, I could pull a vial from the fridge or freezer and make a starter and I'd be ready to go.  I really don't want to get into making slants and subcloning, so I'd prefer to stay with liquid cultures if at all possible.  Does this sound like a reasonable method for keeping my own WLP009 stock?  Should I store them at 4C or -80C?  At 4C, I'm thinking the absolute longest that I'd let it store for is 3 months.  But at -80C, the yeast should be viable for a year or more, right?  Is my concentration of glycerol appropriate? Should the yeast be thawed quickly or slowly from -80C?  Any advice anyone could offer would be appreciated.

I just brewed a batch of a Belgianish strongish ale (9-10%, 12 lbs grain, 6.5 lbs syrup, 4 oz high alpha hops, hopefully I didn't screw it up) with a liter of yeast/gunk from a batch of squash ale brewed in October (so, about 6 months -- not intended.).  I stored it on the top shelf of my fridge, which will frost greens placed up there (the apartment fridge is the food fridge, and ironically enough it is much less nice than the keg fridge).  When I brewed, I let it warm up, flamed the lip of the jar after opening and poured in the slop.  Pouring it into a half full fermenter is a bad idea.  wort everywhere in the kitchen.  then I poured the rest of the wort onto that from on high to get things good and aerated and mixed up.  Oh, I use those big plastic buckets, for better or worse.  After ~40 hours, @ 72 F, it was fermenting like crazy through a blow off tube and it smelled GREAT.  So, I think they will survive for a long time.  I was worried at first.  I collected the yeast off the second batch with that yeast.  It was WLP500 Abbey Ale I believe (if not that then, WLP530 Trappist Ale).

Update : Apparently, this is the last time I brewed any beer.  I saved two liters of yeast from the batch I mentioned in this posting (Oct 2007).  I just started a new beer with all the yeast I had in my fridge from then (liter jar and a small white labs vial worth of stored yeast).  Before any noticeable fermentation was taking place, I left on vacation.  When I arrived today (four days later) I was despondent at the sight of a dry fermentation lock, as this usually indicates that the temp dropped appreciably and sucked the material in the lock into the beer.  In a last ditch effort to save the batch, I prepared a quickie starter with some dry yeast and then cracked open the fermenter to find... a krausen.  refilling the lock allowed me to see that some CO2 was still escaping.  Apparently, the long-stored yeast are somewhat alive (I don't know why).  Not having observed the fermentation myself, I cannot speak as the the vivacity of whatever yeast apparently survived this abuse.  If the dry yeast don't produce some appreciable fermentation in the next 24 or so hrs, I can only assume that the refrigerated yeast survived pretty well and fermented out the batch.

The only thing you can do in this case, as you know, is to let it go for a while.

The suckback may not have been a big deal if the liquid in your airlock was sanitary and the CO2 production started in earnest soon after.  Empty locks are OK if the carboy is blowing out CO2.

Suckbacks are a bigger problem with plastic carboys and (the worst for this sort of thing) PET containers because the walls aren't rigid.  I only use glass carboys for primary, and I always use a blow off tube for the obvious reason but also because it is much, much more difficult to get a suckback with that huge tube.

Follow up : The brew took off with the addition of the dry yeast for perhaps about 24hr.  It's mostly gone now, but it is a nice beer (hence the mostly gone-ness).  I'm actually drinking a bit of wine at the moment to attempt to preserve some of this particular brew I was discussing.