WANI Dictionary

Transformation efficiency

Transformation efficiency (TE) is a measure of the success of a transformation experiment.

i.e., One can say that "In this experiment, TE was 10⁶ CFU/µg plasmid DNA". TE is calculated as follows.

• Count the number of colonies on the plate.
• Determine the amount of DNA used for transformation.
• TE = (Number of colonies / µg DNA)

However, "number of colonies" is not a good measure in general. When incubation time is too long, satellite colonies and overlapping colonies appear on the plate. Some colonies may not be visible when incubation time is too short.

Because of these problems, the colony forming unit (CFU, cfu) is typically used instead of number of colonies. CFU is an estimate of the number of microbial cells that are capable of forming a colony. In an ideal experiment, CFU is same as the number of colonies on the plate.

Using CFU, TE is represented as:

• TE = (CFU/µg DNA)

Definitions in the literature

• Transformation efficiency is the efficiency at which bacterial cells can take up the external DNA and express the gene encoded by it [1].
• Transformation efficiency is defined as the number of colony forming units (cfu) produced by 1 µg of Competent Cells Control DNA (supercoiled plasmid DNA) [2].