Our own GMO. Glowing E. Coli!

We just finished genetics a week ago in biology IB. We’re starting Taxonomy now, but before that, we finished one of my favorite topics with one of the experiments I’ve most enjoyed this year. 

The experiment consisted in, by genetic engineering, trying to insert a gene into E-coli bacteria in an LB agar sample which allowed it to glow under UV light.

For doing this, we prepared four plates of LB agar. The first one didn’t have anything in special apart from LB agar. The second and the third one one had ampicillin (A type of antibiotic) apart from LB agar. The fourth one, apart from this two, had Arabinose on it, which is a type of sugar.

In my group we did also plate 5 and 6 because we had extra LB agar. They were the same than plate 4.

Then we prepared four samples of E-coli for each of our plates. The first two didn’t have anything in special, but in the other two we inserted a vector named P-Glo, which can be seen in the diagram: 

(Diagram credit: http://microbesrule.blogspot.co.uk)

The vector presents 3 important parts. First of all, a promoter sequence of DNA based on the presence of arabinose sugar attached to the green fluorescent gene. This means that for the gene to be translated into a protein, there has to be arabinose sugar in the sample. The green fluorescent gene translates into a protein that allows the organism to glow under UV light. The other important section is the gene of ampicillin resistance, which will allow the bacteria to survive even if there’s ampicillin in the sample. 

For introducing the genes into the last two samples, we poured some vectors of the gene that was a previously copied by a PCR machine into the two last samples with E-coli. Then we putted both samples in a water bath at 42 degrees. This would make the bacterial membrane of the E-coli permeable for the Vector P-glo to pass through and being used by the bacteria.

Then we letted the bacteria to grow and multiply for two days and we got the following results:

-The first plate had a big group of E-coli visible on it, but these ones didn’t have anything in special because we didn’t inserted the vector on them. 

-On the second plate, all the E-coli had died. This is because the Agar had ampicillin on it and the antibiotic killed the bacteria.

-The third plate had E-coli on it but they weren't able to glow. The reasons for this is that even if they had the P-glo vector inside of them (Which gave them the resistance to the ampicillin, the reason why they survived), there wasn’t any arabinose sugar on the sample. Because of this, the promoter didn’t activate, and the glowing gene wasn’t translated into the protein.

-Finally, on the fourth plate we had glowing bacteria! In this case there was arabinose on the sample, so the glowing gene was translated into a protein that gave the E-coli the ability to glow under UV light.

I’ve really enjoyed this experiment and shows me that biology is even more fun than what I expected. We’re starting Evolution now with our other teacher, let’s see how it goes!