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The "Elf": Design

As mentioned, two sorts of bacteria are genetically engineered, Detectors and cleaners.

Two engineered plasmids are inserted into Detectors.


Plasmid 1 comprises of a lac I-induced promoter, an aptamer for atrazine, cheZ gene, RBS and GFP gene. The plasmid enables detectors to appropriately sense the atrazine gradient and move toward. To visualize its motion, GFP is plugged in.


Plasmid 2 comprises of a lac I-induced promoter, a lux-induced promoter, RBS, luxR gene, luxI gene and ccdB gene. This plasmid is a gift from Dr. Lingchong You and Dr. Xuesong Zheng. The circuit aims to control the bacteria density to prevent ecological invasion. In addition, it passes the quorum sensing signal to the ambient space to allow cleaners being attracted.

Two engineered plasmids are incorporated in the design of Cleaners.



Plasmid 3 contains a luxR-induced pluxR, RBS, cheZ and RFP, while Plasmid 4 includes pluxR, RBS and TrzN (the atrazine degradation enzyme). The former plasmid is termed to sense the signal from Detectors and approach them. On their way, Plasmid 4 functions to consecutively degrade the encountered atrazine.