Freezing Bacterial Stocks


• Every time you make a new construct or subclone, you need to freeze it, both in cells and as purified plasmid.

• It needs to be clearly labeled with a sticker. Name your construct in the following way: Example – pMHE001. All plasmids have a lowercase ‘p’ at the beginning, followed by the initials of the person who made it, either an ‘E” or an ‘S’ depending on whether it is an expression construct or a subclone, then a number, sequential in the order you made it.

• Frozen bacterial stocks of expression constructs go in the -80 freezer in the highest numbered “Expression Constructs” box. Subclones go in the Subclone box. Purified plasmids go in the -20 in their respective boxes.

• All frozen stocks MUST be entered into the plasmid database. Be sure to include where the stock is located (which box).

When you are miniprepping your constructs, be sure to keep about 1ml of the liquid culture for freezing, being sure to check the final mini-prepped product on a gel after a testdigest to ensure that it is correct. To this 1ml of culture, add 75ul of DMSO, all in a 1.5ml microfuge tube. LABEL then put in -80 freezer as described above.

1ml of culture
75ul of DMSO goes into the -80°C freezer