Team:Nanjing-China/Design
Biosynthesis of CdS semiconductor
To construct our light-driven system, we first induce the precipitation of CdS semiconductor on the cell membrane. Two plasmids encoding the surface display protein OmpA-PbrR and the nitrogenase are co-transferred into E. coli strain. After Cd2+ is added into the media, the ions specifically bind to PbrR leading to aggregation of Cd2+ ions. At last when S2- ions are added into the media, E. coli cells form CdS semiconductor on the cell membrane because of the aggregation.
Light-driven nitrogen fixation in E. coli cells
To address the problem of electron transduction, CdS semiconductor act as semiconductors imitating the photosynthetic system under illumination. It provided excited electrons to a redox mediator methyl viologen (MV) which then penetrates into E. coli cells and transfer the electrons to Mo-Fe protein subunit of nitrogenase. Mo-Fe protein then utilizes the energy from these electrons to reduce dinitrogen to ammonia. The semiconductor regains its lost electron from sacrificial electron donors.
As a part of biohybrid system, the PbrR protein bears a high specificity. Our system is supposed to self-repair and can be built with a rather low cost. This design is of general applications as OmpA protein is only a surface display machinery for E. coli.
This part of the system is the expansion of our hydrogen production, and it proves that surface display machinery can be expanded to a general principle for biohybrid photosynthesis.
Device
To apply our system to the real world, we also designed a device consists of 3 modules: incubation module, illumination module and control module.
Address
Life Science Department
#163 Xianlin Blvd, Qixia District
Nanjing University
Nanjing, Jiangsu Province
P.R. of China
Zip: 210046
