Making a long term stock of bacteria

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Whenever you successfully transform a bacterial culture with a plasmid or whenever you obtain a new bacterial strain you will want to make a long term stock of that bacteria. Bacteria can be stored for months and years if they are stored at -80C and in a high percentage of glycerol.


  • 40% glycerol solution
  • Day/overnight culture
  • Cryogenic vials/1.5mL microfuge tube


  • Add 1 ml of 40% glycerol in H2O to a cryogenic vial.
  • Add 1 ml sample from the culture of bacteria to be stored.
  • Gently vortex the cryogenic vial to ensure the culture and glycerol is well-mixed.
    • Alternatively, pipet to mix.
  • Use a tough spot to put the name of the strain or some useful identifier on the top of the vial.
  • On the side of the vial list all relevant information - part, vector, strain, date, researcher, etc.
  • Store in a freezer box in a -80C freezer. Remember to record where the vial is stored for fast retrieval later.


  • While it is possible to make a long term stock from cells in stationary phase, ideally your culture should be in logarithmic growth phase.

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