✍️ Author: Dr Eleni Christoforidou
🕒 Approximate reading time: 3 minutes
On this day in the lab, I embarked on an exciting journey into the microscopic world of bacterial transformation. My task? To facilitate a unique experiment which allows E. coli bacteria to clone themselves, thereby producing multiple copies of a gene that has piqued my scientific curiosity.
The goal of my experiment was to modify these ubiquitous E. coli bacteria by introducing a fragment of DNA known as a vector. This vector harbours the gene for a green fluorescent protein (GFP), which will serve as a crucial element in my upcoming investigations. Intriguingly, the vector also carries a gene for antibiotic resistance, a key feature for the success of this endeavour.
Here's why: The agar plates, where the bacteria are left to proliferate overnight, contain an antibiotic that prohibits the growth of unwanted bacterial visitors. Only the bacteria bearing the antibiotic resistance gene - which, importantly, are also the carriers of our GFP gene - can thrive on these plates.
Timelapse: Distributing the bacteria on agar plates for an overnight incubation session, resulting in a thriving colony of cloned bacteria.
Bacterial transformation, the process employed today, represents one of three routes for horizontal gene transfer. This fascinating process enables a bacterial cell to uptake exogenous DNA. For successful transformation, the bacteria must be in a state of competence, which can be artificially induced in the lab.
Our procedure involves exposing the bacteria to calcium chloride under cool conditions, followed by a swift heat shock. This combined assault disrupts the cell membrane partially, creating an opportunity for the DNA to be ushered into the cell. This is where the science of genetic modification takes centre stage, setting the stage for a new chapter in our understanding of these microscopic marvels.