Team:UiOslo Norway/Results
The results are in...
Results
Cloning and Transformation
We confirmed a successful expression of crtE and crtI (figure 1), followed by crtEB and finally crtEBI.
Figure 1: SDS-page of our induced basic parts (crtE, crtB and crtI).
Transformation and successful cloning of crtEBI was confirmed by visually inspecting induced cultures for colour change. Cells with our construct were off-white before we transformed them, but showed red-ish/pink color complexes after transformation and induction (figure 2). Sequencing of the red-colored pellet showed a point mutation (deletion) in the end of the crtI gene. This mutation causes a frameshift, leading to the stop codon not being read during transcription. This is probably the reason we cannot get as much color in our bacteria as we would expect: lycopene is produced, but without a stop codon it will have a C-terminal extension that is not intended. This might affect both the transcription and translation of the pigment, hence lower the efficiency of lycopene production.
Figure 2: Shows the pellet of cells from left to right: empty pBAD construct, uninduced empty pBAD construct, our induced crtEBI construct, and our uninduced crtEBI construct cells (far right)
Solar Cell Assembly
Figure 3: The setup of our solar cell.We assembled our solar cell following the protocol described on our experiment page. We tried the assembly multiple times but had limited success building the solar cell (figure 3) as it produced the slightly higher voltage in the light condition than in the dark. However, the reading observed was not consistent and needs more fine tuning. There are multiple sources of error, like the dryness of the paste, thickness of the different layers and the coating of graphite. Even though we have our suspicions of what to improve, we did not have time to improve it.
Chromatography
We decided to do thin layer chromatography to show lycopene production. Lycopene is a very hydrophobic compound which travels easily with the mobile organic phase, (acetone) and should be found at the top of the mobile phase front. This is also what we observed after the experiment was done (figure 4), but due to varying success in the extraction of lycopene during preparation, we could not use this result to compare the different samples. Because of little time and difficulties we had with extraction, we could only use this to prove that we have produced lycopene.
Figure 4: TLC result in visible (left) and in UV (right). From left to right: induced BBa_K274120, uninduced BBa_K2971004, induced BBa_K2971004.
Future considerations
In the future we want to expand our project, introducing genes to enable the production of other pigments, which will allow an increased absorption spectrum. In addition, we would also like to test our construct in other bacteria, such as D. radiodurans or even yeast, if possible. We consider that in order to make our society more sustainable, we need innovative solutions that can complement already existing solar cells. Our hope is to, over time, technologies such as biogenic solar cells will replace the non-eco friendly energy sources.