What you are given
- Colonies counted: 200
- DNA transformed (ng): 0.01
- Volume plated (µL): 100
- Total recovery volume (µL): 1000
Formula: CFU/µg = colonies · (total / plated) / (ng / 1000)
Molecular biology
How do you calculate transformation efficiency?
Colonies, plated fraction, and DNA mass to CFU per µg. The relationship used is CFU/µg = colonies · (total / plated) / (ng / 1000).
Worked example
Every number below is computed by the calculator, not typed in
The working
- Recovery factor:
total / plated=10x - Efficiency:
colonies · recovery / µg DNA=2.000e+8 CFU/µg
Transformation efficiency 2.000e+8 CFU/µg.
Try it yourself
Two problems, with the working revealed
Problem 1 Transformation efficiency
Work out the result for transformation efficiency.
- Colonies counted: 250
- DNA transformed (ng): 0.05
- Volume plated (µL): 100
- Total recovery volume (µL): 3000
Show the answer and the working
Transformation efficiency 1.500e+8 CFU/µg.
- Recovery factor:
total / plated=30x - Efficiency:
colonies · recovery / µg DNA=1.500e+8 CFU/µg
Open this in the calculator to change the numbers.
Problem 2 Transformation efficiency
Work out the result for transformation efficiency.
- Colonies counted: 200
- DNA transformed (ng): 0.01
- Volume plated (µL): 100
- Total recovery volume (µL): 2500
Show the answer and the working
Transformation efficiency 5.000e+8 CFU/µg.
- Recovery factor:
total / plated=25x - Efficiency:
colonies · recovery / µg DNA=5.000e+8 CFU/µg
Open this in the calculator to change the numbers.
Do it with your own numbers.
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