Cat. no. CSM100 CryoSaver™, Skim Milk, 2ml Cryogenic Vial, 1.3 - 1.7ml Fill 100 vials/box
Cat. no. CSMG100 CryoSaver™, Skim Milk with Glycerol, 2ml Cryogenic Vial, 1.3 - 1.7ml Fill 100 vials/box
Cat. no. CSMG101 CryoSaver™, Skim Milk with Glycerol, Modified, 2ml Cryogenic Vial, 1.3 - 1.7ml Fill 100 vials/box


Hardy Diagnostics CryoSaver™, Skim Milk Media is recommended for the preservation of microorganisms by freezing.

This product is not intended to be used for the diagnosis of human disease.


The use of Skim Milk Media for maintaining frozen stock cultures is common practice in the field of Microbiology. Isolated patient organisms and stock cultures have been known to survive many years in Skim Milk Media when stored at -70ºC. One reference states that some strains may be kept indefinitely at -70ºC and one year at -50ºC.(5)

The CryoSaver™ system is designed for ease of use. Numbered compartments in a durable container protect the CryoSaver™ vials and saves space in the freezer. Each vial has an easy "write-on" label for specimen identification. Accesories include the workstation, which securely holds up to 40 vials for easy one-handed operation when screwing the caps on or off. Inoculation needles and spatulas are available to aid in specimen removal from the CryoSaver™ vial. Colored round cap inserts are available for color coding of the vials. These inserts are available in eleven colors. The caps themselves are available in five colors. See the "Materials Required But Not Provided" section for more information.


Ingredients per liter of deionized water:*

Skim Milk (Cat. no. CSM100):
Skim Milk Powder 20.0gm

Ingredients per 850ml of deionized water:*

Skim Milk with Glycerol (Cat. no. CSMG100):
Skim Milk Powder 100.0gm
Glycerol 150.0ml

Ingredients per 900ml of deionized water:*

Skim Milk with Glycerol, Modified (Cat. no. CSMG101):
Skim Milk Powder 85.0gm
Glycerol 100.0ml

Final pH 6.3 +/- 0.3 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


Storage: Upon receipt store at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration, contamination, or if the expiration date has passed. Product is light and temperature sensitive.



1. Stock cultures should be prepared as soon as the organism is isolated in pure culture in order to prevent genetic variation and inotation. Isolates can be preserved as stock cultures from a non-selective liquid or solid media. Cultures should be 18-24 hours old.

2. To inoculate from a broth, dispense 0.5ml of an 18-24 hour pure broth culture into the Skim Milk Media. Freeze and maintain the culture preferably at -70ºC. Plate out a portion of the culture to check the purity of the isolate put into stock.

3. To inoculate from a solid media, suspend 3 to 4 well isolated colonies in the Skim Milk Media. Mix carefully to ensure an even suspension. Freeze and maintain the culture preferably at -70ºC.

4. To retrieve the organism, thaw rapidly in a 37ºC. waterbath. Using a sterile loop, transfer from the vial to an appropriate non-selective agar media. Do not refreeze the vial. Alternatively, a scraping may be taken from the frozen vial with a sterile spatula (Cat. no. 57949041) and streaked onto a non-selective media. When using this method, the vial should be returned immediately to the freezer before it thaws.

Frozen stock organisms should be subcultured twice before using them as controls.


Skim Milk Media is intended for maintenance of pure cultures. The purity of the culture can be checked by plating a portion of the culture onto an appropriate non-selective media.

Aseptic methods should be used to insure continued quality of the stored microorganism without contamination.

CryoSaver™, Skim Milk Media is formulated for the long-term storage of bacteria. It is not suitable for use in the identification of microorganisms.

This media should not be used if any of the following conditions are present before inoculation:
- the vial shows any evidence of leakage (loss of broth)
- the vial shows any evidence of turbidity, which suggests contamination
- the expiration date has elapsed


The following accessories are available for use with this system:

802501 CryoSaver™ Workstation, securely holds 40 vials 1 workstation
57949041 Spatula, stainless steel, 16.8cm long 1 spatula
T3121 CryoSaver™ Cap Insert, White 500 caps/bag
T3122 CryoSaver™ Cap Insert, Blue 500 caps/bag
T3123 CryoSaver™ Cap Insert, Red 500 caps/bag
T3124 CryoSaver™ Cap Insert, Green 500 caps/bag
T3125 CryoSaver™ Cap Insert, Yellow 500 caps/bag
T3128 CryoSaver™ Cap Insert, Tan 500 caps/bag
T3129 CryoSaver™ Cap Insert, Gray 500 caps/bag
T31210 CryoSaver™ Cap Insert, Lilac 500 caps/bag
T31211 CryoSaver™ Cap Insert, Orange 500 caps/bag
T31213 CryoSaver™ Cap Insert, Violet 500 caps/bag
T31214 CryoSaver™ Cap Insert, Pink 500 caps/bag
T3127 CryoSaver™ Cap Insert, Assorted 1,000 caps/bag

Standard microbiological supplies and equipment such as loops, swabs, applicator sticks, other culture media, incinerators, incubators, etc., as well as serological and biochemical reagents, are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC® 25922
A 24hr 35°C Aerobic Growth**
Streptococcus pyogenes
ATCC® 19615
A 24hr 35°C Aerobic Growth**

** 3 to 4, 18-24 hour old isolated colonies are inoculated into the CryoSaver™, frozen, thawed and streaked onto a non-selective media to check for viability.

User Quality Control


CryoSaver™, Skim Milk Media should appear opaque, and milky white to light tan in color.


1. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

2. Howard, B.J., et al. 1987. Clinical and Pathogenic Microbiology. C.V. Mosby Company, St. Louis, MO.

3. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

4. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

5. Sutter, V.L., D.M. Citron, M.A.C. Edelstein and S.M. Finegold. 1992. Wadsworth Anaerobic Bacteriology Manual, 5th ed. Star Publishing Company.

ATCC is a registered trademark of the American Type Culture Collection.