Irregular experimental operation is common but serious somehow, which could cause infection of disease. The pointed part of used pipettetips and different biological reagent are breeding grounds for bacteria. As the laboratory is the place we went to the most frequently and the garbage usually is not properly processed, this problem needs attention.

    We designed our engineered bacteria in a special container, a garbage lid, to deal with this situation. We put it in the laboratory beaker, constitutive promoter will bring PLA and 2-PE into play, to inhibit the growth in the experimental garbage and release roselike aroma at the same time.
    Taking biosafety into account, we added toxin protein, mazf, as a suicide gene, linking with light-control promoter to prevent our engineered bacteria revealing to the outer environment than the garbage lid.

    We completed the experimental collaboration with ECUST on the LightOn Switch. Upon light exposure, the light-switchable repressor LEVI is induced to form homodimers, which then bind to the operator sequence and repress the activity of promoter by blocking the attachment of RNA polymerase to the promote, represses the expression of CI repressor and initiates target gene. Upon light illumination, LEVI homodimerizes data were normalized to the mCherry expression level in dark conditions. Wavelength of exciting light is 587nm, and wavelength of emitted light is 610nm.(Details can be found on our Collaborations page.)

    mazEF is a toxin-antitoxin module located on the Escherichia coli chromosome and that of some other bacteria, including pathogens. mazF specifies for a stable toxin, MazF, and mazE specifies for a labile antitoxin, MazE, that antagonizes MazF.[11] MazF is a toxic nuclease arresting cell growth through the mechanism of RNA cleavage and that MazE inhibits the RNase activity of MazF by forming a complex.[12]. We used mazF as our killer to ensure biosafety.

    We linked them together. Once the bacteria revealed from the container, in other words, LightOn Switch is open, mazf will express to cleavage the mRNA. And this is the reason why we use light-proof ingredient to 3D-printed our garbage lid. (Details can be found on our Application page.)
    Within the laboratory can be controlled, we demonstrated the efficiency of PLA sterilization. And we also got the most comfortable concentration of 2-PE according to the data of our human practice.(Details can be found on our Human Practices page.)

    After came up with the idea to solve the outer environment, we found the human environment is also interesting. Aiming at another stink caused by bacteria, the bromidrosis is also an unpleasant smell which bothers people around. Two new circuits are applying to the goal of controlling bromidrosis.
    When people sweat, there is specific salt concentration and temperature on the skin. We choose this feature as a starting point, designing a logical gate to produce PLA. Every basic component serves respective functions. dsrA is a temperature promoter from E.coli, more active at 37 degree than 25 degree.[1] The osmotically control promoter proU provides sensitivity to the salt concentration from 0M to 0.3M.[2] And global-regulate protein H-NS which could specifically bind to osmotically control promoter proU, we use it as a specific repressor to inhibit the promoter downstream.[3]