Safe Project Design

1. Choosing a non-pathogenic chassis

     Our project totally involves in four different strains of bacteria, including Nitratireductor pacificus, Bacillus subtilis, Bacillus megaterium and E. coli DH5α. The first three ones were obtained from China Center for Type Culture Collection(CCTCC) and the last one was obtained from Room 6133 of College of Life Sciences, Wuhan University(CLS-WHU). Except for the first bacterium, the last three ones have been identified to Risk Group 1. Though little information is known about N. pacificus, but it’s isolated from the sediment of Pacific Ocean and has the highest 16S rRNA gene sequence similarity with Nitratireductor aquibiodomus NL21(T)-97.3%, which belongs to Risk Group 1.

2. Choosing parts that will not harm humans / animals / plants

     The parts we intend to use are all safe to humans, animals or plants because on the one hand, they have been safely used by many other teams and on the other hand, they don’t encode harmful productions.

3. Substituting safer materials for dangerous materials in a proof-of-concept experiment

     Although our project involves in halogenated organics, which are usually toxic to humans, animals and plants, to guarantee the safety our lab staff, we have considered to substituting our tested substrates in the proof-of-concept experiment to safer ones. But since that if we change the tested substrates, the simulation of our proof-of-concept may be greatly reduced and our final production could only treat less toxic wastewater. In this way, we’ve decided to turn to technicians who have been professionally trained to carry out experiments with these toxic chemicals.

4. Including an "induced lethality" or "kill-switch" device

     We’ve been long thinking about designing an ’induced lethality’ or ‘kill-switch’ pathway in our engineered bacterium because we’re all concerned about Biosafety in biological wastewater treatment. In our human practices, we also communicated with environmental government sectors about the regulations and laws of microorganisms in effluents. Another thing should be mentioned is that the membranes in our hardware/device should have the ability to block microorganisms out of effluents and our engineer bacterium Bacillus megaterium is one of the largest bacteria. We consulted experts about this problem and they told us that there’s still a possibility that microorganisms are leaked into effluents. Although we haven’t thought out feasible pathways, we’ve decided to equip our model with a degerming device downstream.