Paratransgenesis imply the widespread release of GMOs. This, of courses, raises fears and questions about the safety and impacts of the bacteria developed.

The control of these modified organisms poses great technical challenges for synthetic biology, but iGEM teams are in a great condition to improve it! The community has developed a variety of smart kill switch systems that could be adapted for a variety of needs.

  • Facilitate the public acceptance of your construct
  • Control dispersion in a rational manner
  • Avoid unpredictable side effects for people and animals

Kill Switches could be develop in different ways:

  • “Human protection” kill switches, that would promote bacterial arrest in the case of contact with human/animal tissues
  • “Insect dependent” kill switch, one that would allow the bacteria to live only in contact with the insect tissue (or the specific growth media)
  • “Time-bomb” kill switches if bacteria is not consumed by target insect species within a time frame. Detection of insect metabolites or conditions would lead to arrest of bomb cycle.

And much more! Furthermore, these “death signals” can be enhanced in a variety of ways! Positive feedback loops for “toggle switch” -like (1) responses can enhance the effectiveness of control. The choice of toxins or essential targets is also important. This variety of possibilities makes the collaborative framework of iGEM the perfect place for developing this further!

In our project we developed a variation of the “Insect dependent” kill switch which was based on pH, to limit bacteria replication to the midgut. Check more about it here


  1. Chan, Clement TY, et al. "'Deadman'and'Passcode'microbial kill switches for bacterial containment." Nature chemical biology 12.2 (2016): 82-86.