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Revision as of 18:08, 18 September 2015
For many years our society has wanted to have a comfortable life. It has invented and produced a lot of things that allow this comfort [1]. For example, in a typical day we can observe the use of plastic glasses for coffee, plastic bottles for water, disposable cutlery for lunching, plastic bags for supermarket and so others.
In Chile about 25 thousand tons of wastes are thrown into the ocean, where it can be brought back to the coast, sunk or accumulated near the Easter Island [5], but that is not all! Recently, a report published in the Proceedings of the National Academy of Sciences of the United States revealed an emerging and worrying problem: all this plastic thrown to the ocean has starting to fragment in micro-particles which can act as sponges for waterborne contaminants such as dioxins and are swallowed by marine species accumulating in their bodies [3].
Titulo 1
Titulo 2
Titulo 3
Lactadora: Lactate production and pH regulation system
Develop a system that can produces lactate and regulates its concentration. Also, a homoserine lactone molecule would be produce at the same time to activate the second system (PLA production and exportation) by quorum sensing.
What parts did we use? And why?
What modules did we assembly?
How our Lactadora system does work?
Our first system Lactadora consists of E.coli lab strain with a synthetic gene circuit presented at the rigth. We construct the ppH-TetR module to synthetize the TetR protein which is able to repress the pTetR promoter. This synthesis is up-regulated by a pH promoter which is induced when pH is lower than 5.5, otherwise (pH>5.5) there is no TetR protein production. In this last case, the second module (pTetR-DLDH-LuxI) will express the DLDH enzyme to synthetize lactate from pyruvate produced from a glucose molecule and diffuse to medium.
Also, will be expressed the LuxI protein to generate homoserine lactone (HSL), a quorum sensing molecule that can diffuse outside the cell. While concentration of lactate outside the cell increases, medium will turn it an acidic environment; the higher lactate concentration, the lower pH.
When pH>5.5, lactate production is ON.
When pH<5.5, lactate production is OFF.
This way, when pH reaches a 5.5 value or lower, ppH-TetR module will be activated and TetR protein will repress the second module and synthesis of lactate will stop until pH increases again.
PLAdora: PLA production and exportation system
Develop a system that can guarantee human and environmental safety by destroying cells which escape from the controlled culture media.
What parts did we use? And why?
What modules did we assembly?
How our Lactadora system does work?
When HSL molecules diffuse from bacteria 1 to bacteria 2, will bind LuxR protein (completing quorum sensing) and will induced plux promoter so pCoAT and phaC enzyme and phasin-HIyA protein will be expressed at the same time. This system depend of the first system, because if pH is lower than 5.5 (e.g. due to a low consumption of lactate from medium by the second system), there is no production either of lactate and HSL in the first system so there is no induction of plux promoter by LuxR-HSL complex, thereby second system would be OFF.
Represantations of interaction of the different modules of the second system
Arabinita: Safety System
Develop a system that can guarantee human and environmental safety by destroying cells which escape from the controlled culture media.
What parts did we use? And why?
What modules did we assembly?
How our safety system does work?
Essentially, we create a kind of auxotrophic cells which are arabinose-dependent; that means cells need arabinose in the culture medium to survive and grow up. The specific gene circuit is shown in Figure 4. In presence of arabinose pBAD promoter are induced so TetR protein is synthetize to repress pTetR promoter of the PTetR-Lysis gene module.
This allows us to control genetically modified bacteria in the lab, because if bacteria escape from their medium; means there is no presence of arabinose anymore (Figure 5), pTetR promoter will no longer be repressed so cells will produce a lysis toxin which will kill them by destroying its cell membrane.
