THAWING FROZEN MICROORGANISMS
Frozen cultures should be processed immediately upon arrival. If that is not possible, store vials in liquid nitrogen vapor. Alternatively, the frozen material can be stored in a mechanical freezer between -70°C and -80°C for short periods (1 to 5 days). Frozen cultures are stable in the long term only when stored at -130°C or below. Viability of cultures stored between -80°C and -130°C will vary with the nature of the cryoprotective agent and the strain and can only be determined empirically.

One of the most common mistakes when storing frozen material is to place it at -20°C (the freezer compartment of a conventional refrigerator-freezer). Never store frozen cultures in this manner. Storage at this temperature for even short periods will result in rapid loss of viability.

Bacteria
For frozen cultures, thaw the bacterial strain using gentle agitation in a water bath that is set to 25°C to 30°C. v will be rapid; approximately 2 minutes or until all ice crystals have melted. For anaerobic cultures, thaw the vial only in an anaerobic environment; the viability of the cells decrease rapidly if the vial is thawed in an oxygenic environment. Once the vial is thawed, decontaminate the outer surface using 70% ethanol. The entire contents of the vial can then be aseptically transferred to a test tube containing 5 to 6 mL of the recommended medium. Additional test tubes can be inoculated by transferring 0.5 mL of the culture of the primary culture to additional secondary cultures.
https://www.lgcstandards-atcc.org/How_to_Revive_Cultures.asp...