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Safety

Engineering System Controls

We have designed the system to be fail safe, which means that the system's design prevents or mitigates unsafe consequences of the system's failure. That is, if and when a "fail-safe" system "fails", it is "safe" or at least no less safe than when it was operating correctly. Because our system can operate in batch and continuous modes, it is possible to retain the matter inside different storage tanks throughout the process, thus allowing for longer retention should a specific component of the system may need to be repaired.

We have also followed the inherent safety guidelines when designing our project, meaning that the process has a low level of danger, even when things go wrong. Our design minimizes the amount of hazardous material and completely removes (substitute principle) chloroform (solvent generally used for PHB extraction) from the process. We have also removed and sterilized toxic sludge from the main liquid stream early on in the process design (moderate principle).

Applied design safety: Mars

During our interview with Chancellor Dr. Robert Thirsk, we learned that the identification and accessibility of possible points of failure are crucial on the International Space Station. Therefore, our goal was to design our process in such a way to allow astronauts easy and safe access to all components that might fail.

We have identified the most likely points of failure:

The filter clogging after centrifugal separation of liquids and solids
The self-cleaning filter of the stirred-tank bioreactor clogging

Another important safety factor was mentioned by many of the consulted experts, including Dr. Derek Thomas from Made in Space, Chancellor Dr.Robert Thirsk, and Dr. Pascal Lee of the NASA Ames Research Center. They suggested we consider the volatility of the produced plastic, also known as off-gassing. This parameter is important due to the Martian habitat being a closed system, where any off-gassing has high chances of entering the human body through air pathways. Our team didn't find any concerns with the PHB volatility, but further research is required (such as conducting of off-gassing measurements) shall the project be developed further.

Biohazard considerations for the ISS and Mars

NASA is adapting the same biosafety hazard levels as the Center for Disease Control and Prevention (CDC) in the USA. Biohazard Level 1 and 2 materials are allowed on the ISS, while Levels 3 and 4 are generally prohibited, although some may be permitted on a case-by-case basis (Biosafety review board operations and requirements document, 2017). Our team assumes the same guidelines for Martian colonization.

From our interview with Col. Chris Hadfield, we learned that astronauts' safety is one of the most important considerations. Biosafety Level 1 (BSL-1) is suitable for work with well-characterized agents which do not cause disease in healthy humans. In general, these agents pose a minimal potential hazard to laboratory personnel and the environment (Biosafety review board operations and requirements document, 2017). The strain that has been genetically engineered for PHB production and secretion,E.coli BL21(DE3), falls under the BSL-1 description. It is non-pathogenic, and hence can be confidently assumed to be safe for ISS and Mars and to pose a very minimal health risk to astronauts.

Besides physical biocontainment of our engineered E. coli, genetic biocontainment was also considered in case the bacteria were ever able to escape confinement. Genetic biocontainment is the genetic modification of an organism to prevent its survival outside of a controlled system. A simple form of genetic biocontainment is auxotrophy, and this principle was introduced to us by Dr. Sui-Lam Wong. Auxotrophy is defined as the inability of an organism to synthesize an essential nutrient, and so it must be provided with said nutrient in its growth medium to ensure survival. For example, deleting or mutating genes for methionine (an essential amino acid in protein biosynthesis) would force the bacteria to rely on a source of methionine survive. This amino acid could be added to the media in the fermenters and storage tanks for PHB-producing bacterial survival. However, if the bacteria were able to escape from our system, their source of methionine would be lost and the bacteria would not survive. Due to the time constraints of the project, auxotrophy was not able to be implemented into our strain of E.coli, however, it is a possibility for future work.

Lab Safety

We have received safety training seminars in WHMIS 2015, Spill Response Training, Hazard Assessment, Biohazard Handling, Occupational Health and Safety, Incident Reporting and Investigation, and Laboratory Safety from Environmental Health Services at the University of Calgary.

We have learned about the following topics in our safety training:

Lab access and rules (including appropriate clothing, prohibition of eating and drinking, etc.)
Responsible individuals (lab or departmental specialists or institutional biosafety officers)
Differences between Biosafety Levels
Biosafety equipment (such as biosafety cabinets, gloves, laboratory coats, etc.)
Proper aseptic technique
Disinfection and sterilization
Emergency procedures
Transport rules
Chemicals, fire and electrical safety
Emergency and First Aid equipment (fire extinguisher, flashlight, eye washing station, shower, phone, etc.)
Spill response kit
The importance of washing hands upon entering and leaving the laboratory

Figures 1, 2, and 3. The above pictures show some of the safety devices used in our lab. These include but are not limited to a safety shower, eyewash station, first aid kit, and biosafety cabinet.

Due to the safety concerns of handling human fecal matter, we used synthetic feces, or "Syn Poo", in its place. Syn Poo mimics the chemical properties and composition of real feces. The recipe for Syn Poo can be found here.

Works Cited