In order to realize the application of PLA and 2-PE which are produced by the engineered bacteria in daily life, we have designed two kinds of garbage can lids and lotion. According to our project, we will give a detailed account of the principles and functions of our application design.

Garbage can lid

    In order to eliminate foul smell produced from special bacteria in our daily life, we designed a special garbage can lid that has already been made through 3D printing technology. This garbage can lid is used to load the engineered bacteria that are able to produce PLA and 2-PE, which is suitable for use in waste containers of laboratory.
    To ensure biosafety, we introduced light-regulated suicide systems into the engineered E. coli in this section. In addition, in order not to affect growth of the engineering bacteria, we chose light-proof materials to make our garbage can lid, so that the engineered bacteria would not be destroyed under normal circumstances. And only when the bacteria leaked to the external environment, the suicide system would be turned on, and expression of the mazf would crack the bacteria's mRNA and kill it effectively.

    The whole lid consists of three parts. The top is a cover that can be opened, which makes it easy to add bacteria at any time. And the middle portion is a cylindrical liquid reservoir which is used to load engineered bacteria. The bottom of the lid is a circular leaky mesh with holes and transverse grooves evenly distributed on it, which enables the products expressed by bacteria to enter the can evenly and save the amounts of products. The bottom of the lid has an axis connecting the red button at the top. When we press the button, the bacteria in the middle of the lid will flow down the hole at the bottom into the trash can to achieve the purpose of inhibiting harmful bacteria in the trash can and producing rose fragrance.

Lotion

    We designed an lotion to eliminate the bromhidrosis. In order to solve the problem of armpit odor, we have designed an emulsion by using our project. This lotion works by using engineered bacteria to produce PLA and 2-PE to prevent armpit odor. As we have introduced, PLA can inhibit the growth of Corynebacterium and Staphylococcus epidermidis which are the main resource causing armpit odor. Meanwhile, 2-PE can bring us a pleasant feeling by gives off rose fragrance.
    To make this lotion a reality, we turned engineered bacteria capable of producing PLA and 2-PE into lyophilized powder and added it to the emulsion containing nutrients necessary for bacterial growth. When we use this product, we can directly apply the lotion to the underarm. The lotion not only provides nutrition for the engineered bacteria, but also can effectively fix them on the skin, so that the engineered bacteria can work continuously underarm.
    Our lotion comes with an accessory product that contains arabinose. When users do not want the bacteria to produce PLA and 2-PE, by using this accessory product, the suicide system in the engineered bacteria can be activated by arabinose and the toxic mazF is expressed, resulting in elimination of the bacteria themselves. Compared with other fragrance and deodorants in the market, our emulsion is more effective and durable, and it is friendly to the environment and lower in production cost as well.

Future

    We plan to expand the using range of our products in the future and enhance their effectiveness. In the following work, we will continue to optimize the product from the function, practicality, appearance and other aspects to improve our product design. In addition, we will focus more on the safety of our products to apply them to more complex environments, such as household waste and toilet.