Do you have ever imagined what if bacteria call another bacteria and talk about your health? Yes it’s possible… We just need to engineer bacteria in such a way that the could communicate with each other.
Researchers from the Wyss Institute at Harvard University, Harvard Medical School (HMS), and Brigham and Women's Hospital have successfully engineered such bacteria which send molecular signal to other bacteria. Molecular signal sent by Salmonella typhimurium bacteria in response to an environmental cue can be received and recorded by E. coli in the gut of a mouse. This helps the researchers to move forward to design genetically engineered bacteria. Quorum sensing is a type of natural communication system in between bacteria. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density.
Acyl-homoserine lactone is a type of quorum sensing that have not been observed in mammalian gut so it was decided to synthesize such quorum sensing system that may help to transfer information in between bacteria. In order to synthesize this system two different circuits were designed in different strains of bacteria, one is called signaler circuit and another one is called as responder circuit. The signaler circuit contains a single copy of a gene called luxI that is turned on by the molecule anhydrotetracycline (ATC) and produces a quorum-sensing signaling molecule. The responder circuit is structured such that when the signaling molecule binds to it, a gene called cro is activated to produce the protein Cro, which then turns on a "memory element" within the responder circuit. The memory element expresses two additional genes: LacZ and another copy of cro. The expression of LacZ causes the bacterium to turn blue if plated on a special agar, thus producing visual confirmation that the signal molecule has been received. The extra copy of cro forms a positive feedback loop that keeps the memory element on, ensuring that the bacterium continues to express LacZ over an extended period of time. Researchers confirmed that the system was working well in both Salmonella typhimurium and E.coli in vitro so the system was shifted in mice and the results were very promising as fecal samples of over half of the mice were producing 3OC6HSL signal transmission that persisted after two days on ATC.
The researchers hope to continue this line of inquiry by engineering more species of bacteria so that they can communicate, and by searching for and developing other signaling molecules that can be used to transmit information between them and so they could not only transmit information but also provide beneficial effects in the treatment of the disease.
