| Yeast strains can be stored for
short periods of time at 4°C on YPD
medium in petri dishes or in closed vials (slants). Although most
strains remain viable at 4°C for at least one year, many strains fail
to survive even for a few months. Yeast strains can be stored indefinitely in 15% (v/v) glycerol at -60°C or lower temperature. (Yeast tend to die after several years if stored at temperatures above –55°C. Use 2-ml vials (35 x 12 mm) containing 1 ml of sterile 15% (v/v) glycerol. The strains are first grown on the surfaces of YPD plates; the yeast is then scraped-up with sterile applicator sticks and suspended in the glycerol solution. The caps are tightened and the vials shaken before freezing. The yeast can be revived by transferring a small portion of the frozen sample to a YPD plate. |