Although our engineering bacteria won`t and don`t need to release to the environment, we have the responsibility to apply (create) a geneguard device just in case. The genes that we chosed are from the toxin-antitoxin systems, which originally exist in microbial plasmid, and used as “Plasmid Addiction”. So our goals are not only to prevent horizontal gene transfer(HGT) between the engineered bacteria and other wild species , but also to get a higher stability or robustness between different generations through “Plasmid Addiction”. Furthermore, the use of these toxin genes, such as ccdB, can still reduce the use of antibiotics. This feature is already applied by some biotechnology companies.
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Introduction
Biological safety is one of the core issues in synthetic biology. And most safety devices involve toxin - antitoxin genes. Then we come up with a question: can we build a multi-function safety device, not only solve the most major problem of HGT, but also have more significant functions？
One of these is the stability or robustness of the plasmid that contains exogenous gene in engineering bacteria --- that is, the ability to be stable in engineering bacteria between different generations
In this way, the safety device contains two mechanism non-interfering toxin - antitoxin genes. Including a couple to ensure the exogenous gene containing the plasmid is not easy to lost, to a specific engineering bacteria produce dependence, Another pair of toxin gene guarantee plasmid loss unable to live in other living things. To choose gene in the nature of the work style and the previous experimental data, a certain degree of guarantee the feasibility of the idea.
For more information on our Human Practices——Safety, click here.
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Super problems
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Horizontal gene transfer (HGT): It refers to the transfer of genetic material that happens independently of reproduction, especially the foreign gene(or parts, devices, and systems). The target of the geneguard is to prevent its happening.
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Stability: we need the foreign gene(and the parts, devices, systems) to be stable and can work for a long time. It is better if they can addict to our own chassis bacteria.
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Antibiotic Use: It is common to use antibiotic for selecting target genes during the microbiological experiments, which may cause resistance and not good for the environment
Super Power
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Find two proper pairs of toxin and antidote, named the Pair 1 and Pair 2.
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Plasmid Vector: Insert Toxin 1 gene and Antidote 2 gene in the Plasmid vector.
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Bacteria Genome: Insert Toxin 2 gene and Antidote 1 gene in the bacteria genome through transposon. i). When HGT happens, due to the missing of the Antidote 1 gene and its production in the new host, the Toxin 1 will cause the new host to die. ii). When the plasmid vector is missing, the missing of the Antidote 2 will cause the cell to die. And statistically, the intact host cells will be the overwhelming majority. And the Plasmid Addition is established.
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We choose the GFP and RFP as the reporter
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We will choose as many pairs as we could and use mathematical modeling to model the system and optimize the efficiency of the different combinations
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