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From 2012.igem.org

Controlled chemistry plant

As we know, biofilms are always used for chemical transformations in biorefineries. To utilize biofilms more efficiently, we need to control them and make them replaced. Here we expect to use dispersal proteins along with population-driven quorum-sensing switches to accomplish this goal.

We found some paper on related studies. In one of them, the researchers form an initial colonizer biofilm in a microfluidic device, introduce a second cell type called disperser into this existing biofilm, form arobust dual-specied biofilm and displace the initial colonizer biofilm with an extraceller signal from the disperser cells. They also remove the disperser biofilm with a chemically induced switch, and the consortial population could tune. The sketch followed show the mechanism of it.

The two E.coli cell types communicate by using the LasI/LasR QS module of P.aeruginosa. In the disperser cell, the LasI protein(autoinducer synthase) is constitutively produces and synthesizes the QS signal 3oC12HSL. 3oC12HSL freely diffuses into the initial colonizer cell and makes a complex with LasR(LuxR family transcriptional regulator), and the 3oC12HSL+LasR complex induces biofilm dispersal protein BdcAE50Q by activating the lasI promoter. BdcAE50Q disperses biofilms by binding cyclic diguanylate. The biofilm dispersal protein Hha13D6 in the disperser cell is induced upon adding IPTG. Hha13D6 disperses biofilms by activating proteases.

(From "Synthetic quorum-sensing circuit to control consortial biofilm formation and dispersal in a microfluidic device")

We want to develop the system and found a system contains three E.coli cell types, in which the first one can be replaced by the second one, the second one can be replaced by the third one and the third one can be replaced when added some chemical signals. Thus, this kind of controlled chemistry plant can be applied to a three-step chemical reaction and each kind of cells will finish one of them in sequence, just as follows.

Reference:

1. "Synthetic quorum-sensing circuit to control consortial biofilm formation and dispersal in a microfluidic device"

2. "Engineering microbial consortia: a new frontier in synthetic biology"

3. "Applications of quorum sensing in biotechnology"

4. "A synthetic Escherichia coli predator-prey ecosystem"