Compositions and methods for extending storage time of competent cells at -20° C
Compositions and methods are provided for storing prokaryotic cells including competent prokaryotic cells at −20° C. in a buffer so that the cells are suitable for transformation at 0° C. with a foreign molecule.
1. A method comprising:
preparing competent prokaryotic cells;
adding an aqueous storage buffer comprising: i. glucose or an oligosaccharide containing glucose; and
storing the cells in the aqueous storage buffer at a temperature in the range of −15° C. to −30° C. for a period of at least 5 days,
wherein the competency of the cells does not significantly decrease during storage.
2. A method according to claim 1 , wherein the prokaryotic cells are E. coli.
3. A method according to claim 1 , wherein the storage buffer further comprises glycerol.
4. A method according to claim 1 , wherein the storage buffer further comprises DMSO.
5. A method according to claim 1 , wherein the glucose or the oligosaccharide comprising glucose is present within a range of 10 mM-500 mM.
6. A method comprising:
obtaining competent prokaryotic cells in an aqueous storage buffer comprising: glucose or an oligosaccharide containing glucose,
wherein the cells have been stored in the buffer at a temperature in the range of −15° C. to −30° C. for at least 5 days;
raising the temperature of the cells in the aqueous storage buffer; and
after raising the temperature of the cells in the aqueous storage buffer, transforming the cells with a foreign molecule.
7. The method of claim 6 , wherein the foreign molecule is a nucleic acid.