Zymolyase is an enzyme purified from cultures of Arthrobacter luteus, a yeast-digesting bacteria first isolated from brewery sewage. It's used in the lab to dissolve yeast asci for Tetrad Dissection. We use powdered zymolyase from 1.5 ml tube aliquots, stored at 4C.
A good source for powdered (lyophilized) zymolyase is here. Product # 21570001-1 or 21570001-2 for a larger amount (2 KU).
Zymolyase should be stored at -20 C but a small aliquot should be stored at 4 C and be replenished from the master stock as need. At the Buck, you can find the master stock in the dessicator located in the -20 freezer near Katie's bay and the small tube in the box pictured at right in the 4 C refrigerator #3.