Bacterial Transformation

Bacterial Transformation is the process by which a plasmid is inserted into a bacteria (colony).

Entrance Mechanism

Bacterial transformation medium creates an environment for plasmids to enter the bacteria. Normally, the cell membrane’s lipid bi-layer would prevent such entry, since both the cell membrane ($PO^-$) and the plasmid DNA phosphates ($PO^{4-}$) are negatively charged.

There are two parts required for the entry to occur:

1. The transformation medium itself consists of positively charged molecules, which bind to the membrane (but not to the plasmid).
2. A heat shock makes the membrane leaky, enabling the plasmid to enter. Not much heat is required ($42 \degree C$); too much heat ($70 \degree C$ for 2 minutes, for example) would decimate e. coli. on the order of $10^{-6}$. Additionally, too much heat could damage the plasmid DNA.

Confirmation

After bacterial transformation, the bacteria are transferred to antibacterial agar plates containing LB-Kan. The LB-Kan medium ensures that only e. coli. successfully receiving the plasmid can survive. Therefore, if any e. coli. survive at all, it is likely they will have had successfully recieved the plasmid.

Source

The above note is based on the Bacterial Transformation video, as part of the GFP bacteria guide from the ODIN.