Safety

Security is an important issue for all the teams especially environment track. Actually, we pay great attention to safety issues, from laboratory safety to design project safety. We are cautious at every step to ensure that there are no problems with safety.

1.Project safety

In our project, we will put our Noah’s Ark into the environment water, and our engineered bacteria will make contact with water in turbine to accumulate CC. It seems that we have encountered the same problems as other teams - GMO leakage. However, we have set up multiple lines of defense to prevent bacteria from escaping from our ark.

(1). Biofilm

Most bacteria are tightly wrapped by biofilms, owing to the EPS secreted by algae. What’s more, the second plasmid can anchor the bacteria tightly onto biofilm. These together allow them to be fixed on the track and unable to enter the liquid environment inside the turbine.

(2). microfiltration membrane

Water and the compounds dissolved in it can enter and exit the turbine freely, but cells can’t. This is because we add multiple microfiltration membrane to the water inlet and outlet of the turbine. Each single layer of filter can ensure that the bacteria can not pass. We screened the microfiltration membrane carefully and finally chose the Mixed fiber microfiltration membrane.

1).what is microfiltration membrane

In the application of membrane separation technology, microfiltration membrane is the most widely used membrane variety. It is widely used in many fields such as scientific research, food testing, chemical industry, nanotechnology, energy and environmental protection. It is mainly used for the filtration of aqueous solutions, so it is also called aqueous film.

2). mixed fiber microfiltration membrane

Since E.coli has a diameter of 0.5-1.3 μm, finally we chose mixed fiber microfiltration membrane(0.22 μm) , Generally referred to nitric acid-acetic acid mixed cellulose ester microporous membrane, is widely used in many fields such as Pharmaceutical industry, Electronics industry, Public health, Food industry and Sterility testing.

Multiple layers of filtration membrane gives further insurance to prevent the leakage.

(3).” UV tunnel”

Just like the laser tunnel in the movie: Resident Evil, in our design, an ultraviolet device is added at the exit of the turbine end to prevent leakage. Once the bacteria escapes to the exit, they will be killed by ultraviolet rays.

Thus, if the bacteria want to escape, it must go through a long way to the outside. And if that happens, congratulations! Because bacteria will then commit a suicide—that is our last defense!

(4) Kill switch

To prevent bacterial leakage, we designed two toxin-antitoxin pathways to ensure that bacteria will commit a suicide once they leave the environment we provide. In our experiment, one of our pathway worked—”ParD/E”, to see more experiment details you can go to “laboratory-molecular biology lab-experiment” to see how bacteria will be killed.

What’s more, there is another design to provide a more reliable method—a cross-overdox antitoxin plasmid system ensures that the loss of any one of these plasmids can cause death, which can solve the risk of possible horizontal gene transfer.

Since we have two plasmids, we want to design like this to prevent the HGT happening because loss or gain of any one plasmid can lead to suicide by the toxic on it.

Conclusion: Because of time limitation, we had not verified the experiments on UV and microfiltration membranes. The drop rate of bacteria on the biofilm and kill switch had been partially verified. We spent a lot of energy on design considerations and hardware safety considerations. If it could be put into application, we can guarantee that the above defenses can prevent leakage problems as much as possible, and more security experiments will continue to be done.