Up to this point, all the data collected, especially the approximate luminescence intensity of our sender made with the conversion sequence, suggested the luminescence of sender cultures would be sufficient for successful activation of receiver circuit. The next step was to demonstrate successful sender-receiver communication.

The figure above shows the arrangement of the sender and receiver in this experiment. RFP fluorescence, luminescence, and O.D. at 600 nm was measured every 2 hours. With three trials per strain, the following data was procured:

As suggested in our predictions, the receiver was induced by the bioluminescent signal from the sender. Looking at pDawn activation through RFP expression, SY104 was the strain which resulted in the most receiver activation over time. This observation falls in line with the team’s prediction before that a sender with sustained expression light-production will have a greater effect on a receiver which requires a sustained input, like pDawn, than a sender with a transient luminescence output.

NOT DONE YET…

Even though, we were able to establish successful communication between sender and receiver in our proposed system, our results still do describe a 100% reliable communication system. We compared our senders approximated intensity output (8uW/cm^2) to what was listed as the saturation intensity of pDawn, around 14uW/cm^2 (Ohlendorf R. et. al. 2010). It is quite clearly that we are not reaching the saturation point with our sender culture yet as result of this comparison. However, we are close, as there is approximately a 3 fold difference between our intensity and the proposed saturated intensity. Thus moving forward it would be imperative to try and improve some parts of our circuits to achieve this 3 fold difference.

In fact, we have previously noticed that the addition of nonanol (a carbohydrate that serves as a substrate for the luciferase reaction) increased the luminescence output by 3 fold. However, it also killed a lot of our bacteria and thus we would not recommend it as a reliable method of solving the issue. However, as we know have become familiar with the workings of pDawn and the three separate strains, we hope to be able to edit these parts (e.g. switch out a promoter, switch the receiver, etc.) to produce a system which contains a sender that will always reliably activate the receiver to saturation.