The wide use of genetically modified organisms causes concerns on how they will interact in the natural environment. In particular could the genetically modiefied microbes escape our constrains, and outcompete the organisms found in the natural ecosystem? Could the DNA we inserted into a specific bacteria be transmitted, with unknown spread of information?

Biological strategies

Explain kill switches and summarise review/paris bettencourt

Xenobiological strategies

Must be solved by: needs deadman switch = auxotrophy (can be metabolic) no exchange of information = incompatibility Steps in which xenobiology can intervene: Genetic firewall a) XNA used with synthetic nucleotides that can’t be found (either new letters or different sugar backbone) Genetic firewall b) XNA cannot become DNA/RNA and be taken up by a different organism --> incompatibility Semantic firewall: genetic code is different, means something else (e.g. change tRNA synthetase --> triplet means different amino acid) Metabolic firewall: synthetic auxotrophies; uses a synthetic vitamin as key cofactor/ synthetic amino acids etc reference to add

Reference:

1. Wright, O., Stan, G.-B., and Ellis, T. (2013). Building-in biosafety for synthetic biology. (Review) Microbiology, 159, 1221-1235. http://www.ncbi.nlm.nih.gov/pubmed/23519158
2. Okada, K., Minehira, M., and Zhu, X. (1997). The ispB gene encoding octaprenyl diphosphate synthase is essential for growth of Escherichia coli. Journal of Bacteriology, 179, 3058–3060. http://www.ncbi.nlm.nih.gov/pubmed/9139929
3. Søballe, B. , Poole, K. R. (1999). Microbial ubiquinones: multiple roles in respiration, gene regulation and oxidative stress management. (Review) Microbiology, 145, 1817-1830. http://www.ncbi.nlm.nih.gov/pubmed/10463148
4. Schmidt, M (2010). Xenobiology: A new form of life as the ultimate biosafety tool Bioessays, 32, 322-331. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2909387/