Cryovial tubes are suitable for the preservation and cryopreservation of serum, media, cells, tissues, and other reagents. They can be used not only for freezing cells but also for freezing bacterial strains. The methods for freezing cells and bacterial strains differ.
General steps for cell freezing:
Prepare the freezing medium: Prepare a cell freezing medium containing 10%-20%. Common components of cell freezing medium include glycerol, DMSO, FBS, etc. The specific formula can be adjusted according to experimental needs.
Prepare the cells: Culture the cells to 80%-90% density, harvest the cells, and wash with PBS or other buffers 1-2 times to remove cell debris and waste.
Prepare the cell suspension: Add an appropriate amount of freezing medium, suspend the cells in the cell suspension, and evenly distribute them into the cryovial tubes or other freezing containers.
Slow cooling: Place the cell cryovial tubes or other containers at a constant temperature of -20℃ to slowly cool, allowing the cells to gradually cool down to below -80℃.
Fast freezing: Place the cell cryovial tubes or other containers in a liquid nitrogen container to quickly freeze, allowing the cells to rapidly cool down to below -196℃.
Preservation: Store the cell cryovial tubes or other containers in liquid nitrogen until needed for thawing and recovery.
There are many methods for freezing bacterial strains, here we introduce the method using cryovial tubes.
Ceramic bead freezing method
The ceramic bead cryovial tubes contain 12 frosted ceramic beads and a bacterial strain preservation solution. Transfer bacterial strains in the logarithmic phase to the cryovial tubes, invert and mix well so that the bacterial strains are evenly distributed in the preservation solution. Use a pipette to remove the preservation solution; due to surface tension, a layer of preservation solution will cover each ceramic bead, and the bacterial strains will be preserved in this layer of solution. Transfer the cryovial tubes containing the bacterial strains to a -80℃ refrigerator for long-term storage (typically can be preserved for about one year).
When bacterial strains are needed, take the -80℃ cryovial tubes out from the refrigerator, gently shake to disperse the ceramic beads, pick one bead and inoculate it onto an agar plate for streaking, or inoculate it into a liquid medium for bacterial culture. After inoculation, promptly return the cryovial tubes to the refrigerator.
Glycerol preservation method
This method is suitable for medium to long-term preservation of bacterial strains, with a preservation period of more than one year. Since glycerol itself is very viscous and hard to quantify, it is generally mixed with physiological saline at a ratio of 1:1 to create a final concentration of 50% glycerol solution. During use, mix 50% glycerol: bacterial solution at a ratio of 1:1, making the final glycerol concentration 20-30%. Too high or too low glycerol concentration is not conducive to bacterial strain preservation. Transfer the glycerol bacterial strains to a -80℃ refrigerator for long-term storage. When bacterial strains are needed, quickly thaw the cryovial tubes in a 37℃ water bath until the bacterial strains are completely melted, and use them for experiments. This method does not require ceramic beads, so regular cryovial tubes can be used.
