Biosafety classification is based on U.S. Public Health Service Guidelines, it is the responsibility of the customer to ensure that their facilities comply with biosafety regulations for their own country.

DMSO xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0 2.0 ml

Fresh growth medium w/o bacteriaxa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0xa0 8.0 ml

1.xa0xa0xa0xa0 Mix the components in the order listed. When the medium is added to the DMSO the solution will warm up due to chemical heat.

2. xa0xa0xa0 Harvest cells from a culture that is at or near peak density by filtration and centrifugation at 800 x g for 5 min.

3. xa0xa0xa0 Adjust the concentration of cells at least 2 x 10⁶/ml in fresh medium.

4.xa0 xa0xa0 Mix the cell preparation and the cryoprotective solution in equal portions.

5.xa0 xa0xa0 Dispense in 0.5 ml aliquots into 1.0 - 2.0 ml sterile plastic screw-capped cryules (special plastic vials for cryopreservation).

6. xa0xa0xa0 Place vials in a controlled rate freezing unit. From room temperature cool at -1°C/min to -40°C. If freezing unit can compensate for the heat of fusion, maintain rate at -1 C/min through heat of fusion. At -40°C plunge ampules into liquid nitrogen. Alternatively, place the vials in a Nalgene 1°C freezing apparatus.xa0 Place the apparatus at -80°C for 1.5 to 2 hours and then plunge ampules into liquid nitrogen.xa0 (The cooling rate in this apparatus is approximately -1°C/min.) xa0

7.xa0 xa0xa0 Ampules are stored in either the vapor or liquid phase of a nitrogen refrigerator.

8. xa0xa0xa0 To establish a culture from the frozen state place the vial in a 35°C water bath.xa0 Immerse the vial to a level just above the surface of the frozen material. Do not agitate the vial. xa0Immediately after thawing, do not leave in water bath, aseptically remove the contents of the ampule and inoculate into a T-25 tissue culture flask containing 10 ml ATCC medium 1525 bacterized with Klebsiella pneumoniae subsp. pneumoniae (ATCC^® xa0700831).

9.xa0xa0xa0xa0 Incubate at 25°C with the cap screwed on tightly.

10.xa0xa0 Once the culture is established, vigorously agitate the flask and aseptically transfer 0.5 ml to 10.0 ml of bacterized ATCC medium 1525.

11.xa0xa0 Follow the protocol for maintenance of culture.