Competency checking (for estimation: 1.0 * 10⁸ cfu/ug)

Aim

Evaluate Transformation Efficiency of Competent Cell.

Materials

Competent cell: DH5α, JM109 and so on

Plasmid: pCAGGS-MCS, code K88 in MaxiBank

LB medium: ampicillin, for dilution of competent cell

DDW: for dilution of plasmid solution

LB plate: ampicillin

Methods

1. Thaw competent cell at 4.0℃.

2. Dilute plasmid solution to 0.1 ng/uL (1.0 * 10⁻⁴ ug/uL).

3. Add 1.0 uL plasmid solution to 100uL competent cell and keep for 20 min at 4.0℃.

4. By serial dilution, dilute 10 uL competent cell to 0.1x and 0.01x.

5. Streak each 10uL competent cell (original, 0.1x, 0.01x) onto the plate divided into three parts.

6. Incubate O/N (about 14 hours) at 37℃ and count colonies on the plate.

Remarks

Expected result: colonies = *TE (**cfu/ug) * DNA(ug) * Dilution(uL/uL)

Original: (1.0 * 10⁸) * (1.0 * 10⁻⁴) * (10 / 100) = 1,000

Diluted to 0.1x: 100

Diluted to 0.01x: 10

*TE: Transformation Efficiency

**cfu: Colony Forming Unit