Yeast Banking

Over the weekend I added 4 new strains to my yeast library. First of all, a big thanks to Reviled for donating the strains, I'll drop your frozen vials off tomorrow :) Strains were wyeast 1026, 1084, 1469 and 1728. I have the good fortune to have access to a lab at work so all the gear I need is at my fingertips. I am also pretty familiar with sterile techniques and have experience playing around with yeast in a laboratory setting. Messy lab bench, but its sterile...

Anyway, I picked up some yeasties of Reviled last Wednesday, and tried a few of his tasty beers too (awesome Pliny clone!!). Pitched four strains into 300 – 400 mL of 1.040 nutrient rich wort for starters on Friday, and grew them to stationary phase. All starters were grown in erlenmeyer flasks in a shaking incubator at 25oC for nearly two days. A shaking incubator is like a stir platebut without a stirbar and is the recommended method for growing cultures in a lab. 25 degrees is the optimal temperature for sexual reproduction of brewing yeast. Yeasties!!!

Innoculate

Ready to shake

Shake my pretties

On Sunday the cultures were well and truly fermented out. I centrifuged 150 mL of each culture to pellet the yeast and discarded the beer on top. I resuspended the pellets in the remainder of the cultures, the idea being to double the cell count. These ultra thick cultures were pipetted, 15 mL each into 50 mL Falcon tubes and placed into the cold room at 4oC for 24 hours. Incubating yeast at 4oC for 24 hours encourages them to produce the cell wall proteins they need to survive freezing and ensures more viable yeast when thawed. Stationary cultures, perfect!

Pellets

Dry pellets

A lot of yeast!

Today I added 15 mL sterile 30% glycerol to each tube for a final concentration of 15% and froze them at -20oC. I also made some 1.5 mL glycerols and froze them at -80oC for longer term storage. 15% glycerol is the recommended concentration of cryoprotectant for optimal survival. So that’s it, four new strains added. In stock are 1026, 1056, 1084, 1318, 1469, 1728, 2000 and 3068. I have a couple more strains ready for culture, wyeast 1272 and 2124. If anyone wants to add to the library (and get some frozen vials in return), or wants to swap some yeast then let me know and I’ll try to work something out. I will also try to sort out some slants to make sending yeast around the place a bit easier because shipping frozen stuff is a pita.