Exploring Bacterial Transformation at Columbia University: Making E. coli Glow with a Biofluorescent Gene 🪼

During summer school at Columbia University, I had the exciting opportunity to conduct an experiment involving bacterial transformation- under Professor Katherine Kartheiser. The process I took part in allowed me to introduce a fluorescent gene into Escherichia coli (E. coli), which caused the bacteria to express a fluorescent protein visible under UV light. The transformation was successful, and when exposed to UV light, the E. coli colonies glowed, showcasing the power of genetic engineering.

The Method Used: Bacterial Transformation

The first thing we did was prepare the E. coli cells. Normally, bacteria are pretty picky about what they let into their cells, so we had to make the bacteria “competent,” which just means making them more willing to take in foreign DNA. This was done by treating the cells with a solution that made their membranes more porous, so they could absorb the plasmid DNA we were about to introduce.

Then, we added a plasmid—a small, circular piece of DNA that carries the gene I wanted to insert. In this case, the plasmid had the gene for Green Fluorescent Protein (GFP), which is the same protein that causes jellyfish to glow in the dark. We mixed the plasmid with the competent cells and, for good measure, applied a quick heat shock. This made the bacterial membranes even more permeable, helping the plasmid DNA sneak inside the bacteria.

After that, we let the bacteria recover in a nutrient-rich medium for a while, just to give them a chance to heal up and start expressing the new gene. Then came the nerve-wracking part: plating the bacteria on agar plates that had antibiotics. The trick is that only the bacteria that had taken up the plasmid would survive the antibiotic, so those were the ones we were hoping to see grow into visible colonies. The glowing colonies served as an indicator that the transformation was successful.

The outcome can be observed in the Petri dishes I experimented on - the 3 Petri dishes without any glow served as controls to ensure the outcome was entirely a result of gene expression. The bottom right Petri dishes, with its neon green glow, clearly shows the gene expression

Understanding the science-  Genetic Engineering and Fluorescent Proteins

So, why does this work? Essentially, the plasmid we introduced carried a gene for a protein that absorbs light at one wavelength and emits it at another, making it visible as a glow. This is what’s known as a fluorescent protein, and it’s often used in science to track genetic processes, making it easier to observe gene expression and protein function in living cells.

In this case, GFP became a "reporter" for our transformation. Instead of having to wait for a chemical reaction or look for changes under a microscope, we could just shine UV light and watch the bacteria light up. It’s a beautiful example of how science has figured out ways to manipulate organisms at a molecular level, opening up countless possibilities in everything from medicine to environmental monitoring.

All in all, it was an amazing hands-on experience that made the whole process of genetic engineering feel a little more real. The glow of those bacteria under UV light was proof that, with a little bit of knowledge and some lab work, you can alter living organisms to do something completely new.

fresh outta the incubation oven!!!!