Figure 5

Programmed ecosystems developed from designed cellular communications. (A) A synthetic predator-prey ecosystem in E. coli. The predator cell (top) produces the QS signal 3OC₁₂HSL that induces the expression of the toxin gene ccdB in the prey cell (bottom) and causes cell death. Meanwhile, the prey produces another QS signal, 3OC₆HSL, which triggers the expression of ccdA, an antitoxin gene whose expression rescues the predator by neutralizing the toxin CcdB accumulated inside the cell. (B) Synthetic ecosystems with E. coli and Chinese hamster ovary (CHO) cells. The three ecosystems were based on the same foundation - an airborne transmission of transcription system, through which the sender (E. coli) converts ethanol into volatile acetaldehyde and broadcasts it to the receiver (CHO-K1) to alter corresponding gene expression. Top panel: The volatile acetaldehyde produced by E. coli induces antibiotic resistance in CHO-K1 cells, leading to a commensal community. Middle panel: The acetaldehyde from the sender induces the apoptosis of the receiver, creating amensalism between the two species. Bottom panel: E. coli rescues the CHO-K1 cell by triggering antibiotic resistance through volatile acetaldehyde, and in the meantime, the CHO-K1 cell benefits E. coli by degrading ampicillin that is toxic to E. coli, resulting in a mutualistic consortium. (C) An engineered biofilm-forming system that consists of two communicating E. coli species. The disperser cell (bottom) produces AHL (3OC₁₂HSL) to trigger the expression of the gene bdcAB50Q in the initial colonizer cell (top), leading to the dispersion of the biofilm formed by the initial colonizer cells. Meanwhile, the biofilm formed by the disperser cells can also be dispersed by inducing the expression of the dispersal protein Hha13D6 with external inducer IPTG. The combination of the two steps allows the replacement and removal of biofilms in a programmed manner.