The laboratory environment can be a hazardous place to work. Safety is a very important aspect of working in a laboratory. Our team is working in the safety level 1 lab, which is the lowest safety level and is sufficient for all our experiments. Our team is fully compliant with the safety and security rules of the iGEM competition. in order to provide a clean and safe laboratory environment for team members to conduct their research, we classified reagents and drugs, placed hazardous reagents into the special storage cabinet, and marked them for warning.
Fig.1 Classified medicine storage cabinet
We also periodically worked with our college's safety committee to examine our facilities. Nianhui Zhang, the PI of our team, is responsible for the biosafety of our lab. He can provide us with reliable safety guidance because he has 26 years of teaching experience. Before starting work in the lab, all team members must undergo comprehensive training in safety knowledge and experimental operation under the guidance of staff and teachers.
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Fig.2 Lab bench |
Fig.3 Biological safety cabinet |
SCU-China 2023's project SRBioQuencher, worked to solve the problem of sewer pipe corrosion and hydrogen sulfide gas production caused by sulfate-reducing bacteria by introducing engineered E. coli. The design of engineered E. coli specifically includes biofilm degradation, quorum sensing quenching, antimicrobial modules. In our program, E. coli will be placed directly into the drainpipe, and the effluent from the pipe will pass through the various levels of the drain to the sewer treatment plant, where the effluent will be processed and discharged to natural water bodies.
In the process of pulling out an iGEM project of environment track, we need to consider both the effect on humans and the environment when introducing a newly engineered bacteria. In our project, the engineered E. coli may directly or indirectly pass through or affect these processes or humans, which may have ethical implications:
| place | sewer pipe | sewer treatment plant | natural water body |
|---|---|---|---|
| possible areas of influence | bacteria in sewage, biofilm on pipe walls, sewer workers | wastewater treatment process | Living organisms in natural water body, city residents |
*According to the principle of biocontainment, engineered bacteria should be designed to be inaccessible to natural water bodies.
Since the discharge of engineered microorganisms into the natural environment is uncontrollable, our bacteria are designed to be strictly confined inside the sewer system, an artificial system that is closed to the outside environment.
Currently, the drainage pipes and devices in wastewater treatment plants in our cities are made of reinforced concrete and cast iron. We should be wary of corrosion caused by biofilms formed by engineered bacteria on the pipe walls leading to leakage problems. The regulation of the industry suggests that workers who may contact wastewater are required to wear protective suits and oxygen masks. These regulations avoid the direct contact of workers with engineered bacteria.
To maximize the elimination of GMOs from entering natural water bodies and reaching the residents, we used lactate operator and two lethal genes, ccdB and ccdA, to establish a kill switch based on the predator-prey model. The switch allowed the engineered E. coli to commit suicide in the effluent with a low concentration of the quorum sensing molecule, AHL. The latter would die in the microbial treatment cell and UV sterilization process during the treatment of wastewater.
While introducing new metabolic streams, the inherited colonization characteristics, and metabolic pathways of E. coli, such as parthenogenetic anaerobiosis and acid production, will still affect the environment of the release area. However, it is the gas and water levels inside the sewer pipes that pose the main safety risk. Special consideration needs to be given to the fact that the flow of wastewater treatment downstream may be affected by the composition of the wastewater, including pH, level of carbon, and nitrogen sources. After interviewing experts, we learned that the pH of treatable wastewater ranges from 6-9 and that carbon and nitrogen sources can be supplemented depending on the actual content. Putting in E. coli will not affect the normal wastewater treatment process.
The different upstream sources influence the composition of the wastewater. It varies greatly in different areas of the sewer. There are still no reliable findings on whether the engineered E. coli will interact with other microorganisms in the sewer system. Therefore, we planned to explore these interactions by ourselves, through hardware and modeling, to confirm that our engineered bacteria are harmless.
The cost and social impact of introducing a new technology into engineering applications should be seriously considered by local government. Although the concept of genetic engineering has been popularized by mass media to city residents, there’s still a skeptical voice. Also, engineering experts believe that synthetic biology products mean high prices and high risk before they are approved by the biosafety department and produced in large quantities. All in all, the proof of the engineering bacteria with good performance and safety is the basis of dispelling these doubts.
