Liquid nitrogen preservation of standard inoculum: gas-phase storage.

Liquid nitrogen storage was the most satisfactory of several methods tested for supplying standard Streptomyces viridoflavus inoculum for laboratory and pilot plant experimentation. Shake-flask cultures were subdivided into sterile cotton-plugged ampoules and stored in the gas space of a liquid nitrogen refrigerator. There were no detectable changes in viability or in candidin-producing capacity over a 12-month test period. The procedure also proved satisfactory with all other organisms tested.