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  • FAQ: How should I calculate the transformation efficiency of NEB 5-alpha Competent E. coli (Subcloning Efficiency)?


    Transformation efficiency (TE) equation:
    TE = Colonies/µg/Dilution
    Colonies = the number of colonies counted on the plate
    µg = the amount of DNA transformed expressed in µg
    Dilution = the total dilution of the DNA before plating

    TE calculation example:
    Transform 1 µl (1 µg) of 1 mg/ml pUC19 DNA into 50 µl of cells, outgrow by adding 950 µl of SOC and dilute 10 µl up to 1 ml in SOC before plating 100 µl. If you count 250 colonies on the plate, the TE is:
    Colonies = 250
    µg DNA = 1.0
    Dilution = 10/1000 x 100/1000 = 0.001
    TE = 250/1/0.001 = 2.5 x 105 cfu/µg