# Transformation efficiency - Help! (May/08/2006 )

Hello,

I needed some big help in calculating transformation efficiency.

If the DNA concentration was 15 ng/ml and the plating volume was 100ul. The final volume at recovery was 100 ul. The number of transformants I got were 67. How can I calculate the transformation efficiency in units of transformants/ug of DNA.

I will really really appreciate any help in this.

Thanks.

`H`

-heena-

Honestly,

Did you use 900ul of SOC or LB? Here is the example that I came across a while ago in some catalogue. Worh out like this

"After 100ul of competent cells are transformed with 0.1ng of uncut plasmid DNA, the transformation reaction is added to 900ul of SOC medium (0.1ng DNA/ml). A 1:10 dilution with SOC medium (0.01ng DNA/ml) is made, and 100ul is plated on each of two plates (0.001ng DNA/100ul). If 200 colonies are obtained (average of two plates), whats the transformation efficiency?

(200 cfu/0.001ng) x (1ng/ 10 to the power of -3 ug-microgram) = 2x10 to the power of 8 cfu/ug DNA

Hope this helps.

-Jiang M-