Bacterial transformation

Today in the lab I did a bacterial transformation experiment, then left the bacteria to grow on agar plates overnight, so that they would clone themselves and produce multiple copies of a gene I am interested in.

For my experiment today, I transformed some E. coli bacteria with a piece of DNA known as a vector, which contains the gene for a green fluorescent protein (GFP) that I will be using later on for my subsequent experiments. The vector also contains a gene for antibiotic resistance. This is because the agar plates I am using to grow these bacteria on, contain an antibiotic which will prevent the growth of any other bacteria, apart from the ones carrying the antibiotic resistance gene (and therefore also the GFP gene).

Timelapse: Spreading the bacteria on agar plates which will be incubated overnight to produce clones.

Detailed methods of today’s experiment

Transformation is one of three processes for horizontal gene transfer, in which exogenous DNA is taken up by a bacterial cell. For transformation to occur, the bacteria must be competent. Artificial competence is induced in the lab by exposing the bacteria to calcium chloride under cold conditions, followed by a heat shock. This partially disrupts the cell membrane, allowing the DNA to enter the cell.