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  • Chassi
    • Probiotics
    • Promoters
    • Reporter genes
    • Toxin-antitoxin system
    • Vectors
    • Signal peptide
  • Metabolic engineering
    • p-Coumaric acid
    • Resveratrol
    • Lycopene
    • β-carotene
    • Saffron
    • Astaxanthin
    • Zeaxanthin
  • Miraculin
  • Chromoproteins
  • Safety experiment
  • Results
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  • Kinetic model
  • Modeling tutorial
  • Toxicity model
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  • Resveratrol group
  • Carotenoid group
  • Chassi group
  • Advisors
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  • Yoghurt +
  • SynBioDay
  • Biosafety and ethics
  • Public opinion
  • High school & media
  • BioArt
  • A LactoWorld
  • Killswitches
  • Patent
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  • Safety form
  • Protocols

One major risk that the synthetic biology community needs to address is the spread of modified organisms in nature and associated repercusions. Many iGEM teams have addressed this issue by introducing so called killswitches in their design. A killswitch system reduces the risk of bacteria spreading in nature by making it unable to survive without certain conditions. A classical killswitch works by the use of a reagent not present in nature that hinders the expression of a toxin. When the bacteria is released to the enviorment, the reagent is no longer present and the expression of the toxin is released.

While this sounds like a good solution there are flaws in the system. A large problem is mutations and genetic recombination that destroys genetic code for the toxin, and therefore making the bacteria able to survive once again. We would also like to argue that the modified bacteria fitness is so much lower than the wild type that the chance of survival in nature is low. To prove this we preformed a competition test,which showed that our modified bacteria would become outcompeted in a couple of days. Therefore we concluded that a killswitch was not needed in our project.

After a long discusion about killswitches our team reached a couple of conclusions. Our first conclusion is that the best killswitch would be one that removes a function of the bacteria much like BGU_Israels p.a.s.e. 2 part. To gain a new function from scratch would need an horizontal genetransfere from another bacteria, or a massive amount of mutations and recombinations. While to loose a function, like producing the toxin, could happen with a single mutation or recombination. Our second conclusion is that the problem with iGEM teams approch to killswitches today is that they do not confirm the effectiveness of the killswitches. How well does to bacteria survive outside the lab? This can easily be tested with an competition test as seen in our project. A killswitch should not simple be inserted as a way to automaticly acheive biosafety criterias without being tested. We hope that future iGEM teams will focus on a low chance of survival outside of the lab, with or without killswitches.