Team:Nanjing-China/safety

Since our genetically engineered bacteria will be used in the outdoor environment to deal with pollutants. We must take the safety of these bacteria into consideration, in case they cause potential hazard. We have two designs to make our products safe to use.


First of all, we designed a suicide plasmid to let bacteria die in line of duty after their disposition of the pollutants. This plasmid will make the engineered bacteria live on the substance they deal with, if the certain substance is missing, the lysozyme will be produced and the bacteria will all die. However, there is a problem related to the culture of the bacteria since we cannot use certain pollutant to “bring up” them. So we put a lactose operon in parallel on the plasmid to make it possible to culture the bacteria by IPTG. (For detailed instruction, please refer to our Project-Suicide section part)

However, even though we have our suicide plasmid to stop genetically engineered bacteria from spread to the natural environment arbitrarily, there are still possibilities that our recombinant plasmids can be obtained by wild type bacteria. So we found an idea to stop the process of horizontal gene transfer by making the recombinant plasmids “toxic” to wild type bacteria.


We plan to add a constantly expressed lysozyme to every recombinant plasmid, and add some anti DNA which can result in the expression of some anti RNA to lysozyme to the genomes of the engineered bacteria to protect our bacteria from the “toxin”. Although it can be hard to put gene to the genomes of the bacteria, we figured out a way to do so. A kind of plasmid called CRIM plasmid [ Zhou L, Zhang K, Wanner B L. Chromosomal expression of foreign and native genes from regulatable promoters in Escherichia coli[M]//Recombinant Gene Expression. Humana Press, 2004: 123-134.] will help with the process.

However, we all know that the antisense RNA technique may not as efficient as expected, even though we plan to add several anti DNAs to the genomes and use bioinformatics to design high-efficient ones, the anti RNA may not be enough to protect the genome. So we also give our Plan B here, which uses the same principle, but uses inhibit operons (we use lactose operon here as an example) instead of antisense DNA.

Although our team members really care about the biosafety and show great interest in the designs above, a summer vacation’s time can be only enough for us to accomplish the first part of the safety part, we are willing to try the second part in the future.