To calculate transformation efficiency:
- For each batch of competent cells you make, it's a good idea to calculate transformation efficiency.
- Transform the cells with a known amount of DNA (e.g. 1μg DNA into 100μL cells).
- Plate several volumes of cells onto selective plates (10μL, 50μL, 100μL cells per plate).
Transformation efficiency = # colonies/amount of DNA on the plate (μg/mL)
e.g. you count 1500 colonies on a plate
100μL cells
+ 1μL DNA @ 1μg/mL
+600μL SOC
711μL → plated 10μL
10/711 = 0.014 = "amount of DNA on the plate"
1500 colonies / 0.014 = ~1x105
Ideally, "ultra-competent cells" will have a competency of about 107 or 108.
