Hello Osama,

You can use them without freezing. Just make sure that they will not stay at room temperature too long, because the cells number will decrease and so is the transformation yield.

Edit: Just to be sure: if you are preparing cells for stock or for later use, they should be frozen.

You can use the competent cells immediately after preparation, but don't forget to keep it on ice during or prior to the transformation. Keeping at RT may cause duplication of cell (increase in number) which may affect your transformation efficiency.

While for the remaining un-used cells you can store at -80OC for future use.

Dear Osama

While preparing the cell, at last step keep them in liquid nitrogen for 5 min and then incubate them on ice till further use.

All the best

Chet Ram

As you are following proper protocols, your cells are already in chilled state, so go ahead and use them.

I normally make 100ul aliquots separately in Eppys and store at -80 until further use. It works well. Even you can slo use immediately for transformation.

I am totally agreed with Mr. Antony Ceasars. I am also doing in same way.