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 where we spent most time a day, the improperly processed garbage should be taken into consideration.
    We designed our engineered bacteria in a special container: a garbage lid, PLA and 2-PE will be released to inhibit the growth in the experimental garbage and release roselike aroma at the same time.

    Taking biosafety into account, we added mazEF to our circuit, which is a toxin-antitoxin module located on the Escherichia coli chromosome and some of other bacteria, including pathogens. mazF specifies for a stable toxin protein, and mazE specifies for a labile antitoxin, which antagonizes toxin protein[1]. mazF is a toxic nuclease arresting cell growth through the mechanism of RNA cleavage and mazE inhibits the RNase activity of mazF by forming a complex.[2]. In our project We used mazF toxin protein as our killer to ensure biosafety.

    mazF, as a suicide gene, is linked 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 activating light is 587nm, and the wavelength of emitted light is 610nm.(Details can be found on our Result page.)
    We linked mazF and LightOn Switch together. Once the bacteria is revealed from the container, in other words, LightOn Switch is open, mazF will be expressed to cleavage the mRNA. And this is the reason why we use light-proof ingredient to the 3D-printed garbage lid. (Details can be found on our Application page.)
    Within the laboratory, we demonstrated the efficiency of PLA sterilization. And we also obtain the most suitable concentration of 2-PE according to the data of our human practice.(Details can be found on our Human Practices page.)

    Aiming at another stink caused by bacteria, the bromidrosis is also an unpleasant smell which bothers people around. Two new circuits are applyied 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, designed and construced an engineered E.coli strain with a logical gate to produce bacteriostatic PLA. Every basic component serves respective functions. dsrA, a temperature-controlled promoter from E.coli, is more active at 37 degree than 25 degree.[3] The osmotically control promoter proU shows sensitivity to the salt concentration from 0M to 0.3M.[4] We used the global-regulate protein H-NS that could specifically bind to osmotically control promoter proU as a specific repressor to inhibit the promoter downstream.[5]