Culture System: Xenic; grown with mixed bacteria
CPMB-5 Cryoprotective Solution
DMSO 1.0 mL
2.5 M Sucrose 0.8 mL
L-Cysteine/Ascorbic Acid Solution 0.2 mL
CPMB-2 Basal Solution 6.0 mL
HIBS 2.0 mL
CPMB-2 Basal Solution
Yeast Extract 60.0 g
K2HPO4 1.0 g
KH2PO4 0.6 g
NaCl 2.0 g
Distilled water 1.0 L
Autoclave for 15 minutes.
L-Cysteine/Ascorbic Acid Solution
L-Cysteine-HCL 1.0 g
Ascorbic Acid 0.1 g
Distilled water 10.0 mL
Add 9.0 mL of distilled water to a 20 mL beaker and dissolve the first two components. While stirring, adjust the pH to 7.2 with 10N NaOH (approximately 0.7 mL). Adjust final volume to 10 mL with distilled water and filter sterilize. Solution should be used soon after preparation. Discard any unused solution.
Harvest and Preservation
- Harvest cells from several cultures that are in the late logarithmic to early stationary phase of growth. Place culture vessels on ice for 10 min.
- Invert tubes 20 times and centrifuge at 200 x g for 5 min.
- While cells are centrifuging, prepare the cryoprotective solution.
- Place 1.0 mL of DMSO in a 16 x 125 mm screw-capped test tube and ice until solidified.
- Add 0.8 mL of the 2.5 M Sucrose solution, remove from ice and invert until the DMSO is liquefied. Return to ice bath.
- Add 0.2 mL of the L-Cysteine/Ascorbic Acid Solution to the DMSO solution and mix.
- Add 6.0 mL of the CPMB -2 Basal Solution and mix.
- Add 2.0 mL HIBS and mix.
- Resuspend the cell pellets and pool to a final volume of approximately 10 mL with the supernatant. Make a determination of the cell density and adjust the concentration of the cells between 5 x 105/mL - 1 x 106/mL using fresh medium. If the cell concentration is below 5 x 106/mL, centrifuge the cell suspension and resuspend the pellet in a volume that will yield the desired concentration.
- After the cell concentration is adjusted, centrifuge as in step 2.
- Remove as much supernatant as possible and determine the volume removed.
- Resuspend the cell pellet with a volume of the cryoprotective solution equal to the volume of the supernatant removed. Invert the tube several times to obtain a uniform cell density.
- Dispense 0.5 mL aliquots into 1.0 - 2.0 mL plastic sterile cryules (special plastic vials for cryopreservation).
- Place the vials in a controlled rate freezing unit. Use the following cooling cycle: From room temperature cool at -10°C/min to the heat of fusion; from the heat of fusion to -40°C, cool at -1°C/min. At -40°C plunge into liquid nitrogen. The cooling cycle should be initiated no less than 15 and no more than 30 minutes after the addition of DMSO to the cell preparation.
- Store ampules in a liquid nitrogen refrigerator until needed.
- One day before thawing a frozen ampule inoculate two tubes of ATCC medium 1171 with the bacterial flora only. Incubate the tube on a 15° horizontal slant at 35°C.
- On the following day reduce the volume of the culture from 8.5 to 8.25 mL and add 1.75 mL of HIBS. Invert gently several times to mix.
- Remove the frozen ampule from liquid nitrogen and flame gently at the base of the cap. Remove the cap and aseptically add 0.5 mL of the modified medium prepared in step 12. Place in a 35°C water bath until thawed (2-3 min). Note: Manipulations of the ampule before placing in the water bath should be done as quickly as possible to avoid warming of the contents at a suboptimal rate.
- Transfer contents of the thawed ampule to a dram screw-capped vial (vial holds approximately 4.0 mL).
- Add 2.5 mL of serum supplemented medium prepared in step 14. Tighten the cap and incubate on a 15° horizontal slant at 35°C for 2-3 hours.
- Ice the vial for 10 minutes, invert gently 10 times, and centrifuge at 100-200 x g for 5 min.
- Aspirate the supernatant leaving approximately 0.5 mL. Note: Do not aspire the pelleted material.
- Replace the supernatant with 3.0 mL of ATCC medium that has been inoculated with the bacterial flora.
- Incubate the vial on a 15° horizontal slant at 35°C with the cap screwed on tightly. Observe the culture daily and transfer when many trophozoites are observed.