There is still a lot of work to be done in order to correctly demonstrate that our “intelligent biosensor” works as expected. Further testing with different concentrations of the compound of interest is needed so that we can verify that, under specific conditions, only one of the reporter proteins will be expressed. With our project, we were able to demonstrate that the PoPS amplifiers work as expected; however, we couldn’t prove that our genetic frame behaves the way we anticipate. Therefore, in the future, we must do more tests measuring the fluorescence of our whole cell reporter at different concentrations of the substance of interest and analyze the results so we can provide evidence that this genetic frame works properly.
Once we have demonstrated that our genetic device works properly in its current configuration, more research must be done to prove that this genetic frame is useful to develop a whole cell bacterial reporter that works for many types of compounds. In order to do this, a new system of promoters must be developed and tested so they can be used instead of the pBAD family. It would also be useful to test this genetic frame using a different set of reporter molecules instead of the three fluorescent proteins used in our device.
A number of other iGEM teams from previous competitions have developed parts that could be useful to continue with this research. For example, the 2009 Cambridge University Team also developed a series of reporter molecules of different colors that could be used instead of the fluorescent proteins in our device. Additionally, the Registry has a lot of promoter BioBricks that can be used instead of the pBAD family. However, these additional promoters must be modified via mutagenesis to produce weak and strong varieties as the British Columbia team did in 2009 in order to work with our genetic frame. We encourage other teams that are interested in developing these “intelligent biosensors” to contribute and develop new biological parts that can be used to extend the uses of our construction and further validate it. We hope that the contributions we made with our project will prove useful for the creation of this new generation of whole cell biological reporters.
Why are we so interested in whole cell “intelligent” biosensors? We believe that these organisms will prove useful in a wide variety of situations. Initially our purpose was to develop these sensors in order to detect toxic chemicals in water, soil or any other natural habitat. In this field, biological sensors have proven to be a great and inexpensive way to assess the presence of a specific pollutant; for example, if you wish to know if a lake is contaminated with a heavy metal you can just take a sample of that lake’s water and use a biological sensor to analyze it. The results can be measured relatively fast and without the need for expensive equipment, you just have to check for the presence of the reporter molecule. With “intelligent” bacterial reporters, it is easier to estimate the concentration of the substance of interest in the system.
Even though the environmental applications are the most obvious and easy to implement, we began to explore different uses for our “intelligent” biosensors. One of the great advantages of these “intelligent” biosensors is that they respond differently depending on the concentration of the target compound, so we began to think about situations in which it would be useful to have an organism that is able to respond differentially depending on the concentration of a compound. We realized that there were a lot of situations in which we could apply these types of mechanisms that are not necessarily related to environmental science. For example, they could be used as simple medical alternatives to expensive tests.
However, there was an alternative application for our genetic frame that we found even more attractive. Instead of producing a reporter molecule with the sole objective of indicating the presence of a compound, we could produce an enzyme or another biological component that reacted in some way with the target compound. An application for these types of systems in the future could be the detection of glucose in blood and if the concentration of sugar is low, the reporter molecule produced would be glucagon, but when the concentration is high the molecule produced would be insulin. Industry could also benefit from these types of systems, for example in the implementation of chain reactions within a bioprocess. Instead of detecting different concentrations of a compound, the sensor could detect different compounds and produce a specific enzyme depending on the compound detected. The possibilities are endless and these are just two examples that we imagined when we were brainstorming about possible applications for our “intelligent” biosensor.
But before any of the previously discussed possibilities can become a reality, we must continue to prove the current biosensor and make sure that it works as we expect it to. We encourage future iGEM teams to come up with new and novel implementations of this system and adapt our construction to their needs. We are confident that in the future, these new type of sensors and genetic constructions will be commonplace in the industry and will help in the development of new, powerful tools for the environmental, medical and industrial areas.