Team:HK SSC/Implementation
Proposed Implementation
Safety considerations
Although S.elongatus UTEX 2973 is considered harmless to humans and to the environment, it is crucial for us to keep our engineered strains contained as the engineered plasmids can be transferred to wild strains if the engineered strains are leaked out of the laboratory. Increasing awareness from the public concerning biosafety and the environment also reminds us to keep our work under control even when upscaling. Photobioreactors will be kept sealed from the natural environment to prevent gene exchange of our strains with wild strains. We will also educate end-users and the public that S.elongatus UTEX 2973 is not toxic to prevent spread of false worries.
End-users
Nylon manufacturers are expected to be the largest end-user of our project, along with drug manufacturers. Synthetic biology is still an unfamiliar topic to many people in Hong Kong, so it would not be surprising if manufacturers feel reluctant to use our product. To prove that our biological production method is reliable, we will need to conduct assays showing the quality and yield of the valerolactam we produce. Prediction of our produce can also let manufacturers gain insight of our production in the long run so they know what to expect. Energy consumption analysis should be conducted for manufacturers interested in the green aspect of our production.
Optimizing BG-11 Manganese concentration to minimize costs
In our visit to Geb Impact Technology, we learned that the main obstacle of commercialization of cyanobacterial/algal cultivation is the cost. To address this problem, we carried out an investigation of the effect of different concentrations of manganese in BG-11 medium on the growth of S.elongatus UTEX 2973, drawing a growth curve. In the investigation, we learned that the growth of S.elongatus UTEX 2973 was the most outstanding when 0.1X manganese was used in the BG-11 growth medium. This information helps us formulate a BG-11 growth medium best for S.elongatus UTEX 2973. We can achieve optimal production with precise amounts of resources, allowing our production to be efficient. Improvement in efficiency can push us to be more outstanding in the petrochemical synthesis of lactams, letting synthetic biology gain more attention and advance further.
Photobioreactor design for large scale cultivation
Optimized growth conditions alone are not enough for commercialization of technologies involving cyanobacterial cultivation. Another difficulty in the process of its commercialization is that the cyanobacteria do not necessarily grow as well in a large scale versus in a small laboratory scale. Photobioreactors specific for large-scale cultivation need to be designed. We envision a flexible photobioreactor that can meet the specific growth requirements of S.elongatus UTEX 2973 while being eco-sustainable. The photobioreactor should be situated in a glass room, where temperature and lighting can be better controlled. The photobioreactor consists of two connected parts, a shaded column, and tubes exposed to natural light. Growth medium with cyanobacteria cells are circulated through the tubes and column, photosynthesizing in the tubes and being collected in the cooler column before they overheat. Depending on the weather, sunlight may not be strong enough for cells growth, so lights can be switched on to assist. The rate of flow of the medium can be adjusted automatically to maintain the optimal growth temperature of the cells. A rotary air pump bubbles air into the tubes to supply carbon dioxide to the cells. Membranes that capture carbon dioxide can be paired with the air pump to enhance the carbon dioxide concentration provided to the cells. These features are important to control and optimize the growth parameters for the cyanbacteria, allowing us to maintain production levels. Manufacturers looking to us our valerolactam would be more confident in our technology knowing that we can sustain stable production levels with such a photobioreactor.
Extraction of valerolactam
Limited by the pandemic, we have yet to be able to characterize the ability of our engineered S.elongatus UTEX 2973 to produce valerolactam and so our plans for the extraction of valerolactam are still preliminary. One method is establishing a secretion pathway in S.elongatus UTEX 2973 for it release the valerolactam. This method saved cyanbacteria cells for larger continuous production, but we may face challenges when dealing with the organism's metabolism pathways. Another would be lysing the cell then extracting the valerolactam through liquid-liquid extractions, using mild solvents that can also ensure the purity of the valerolactam. This method is more direct, allowing us obtain and process the valerolactam for it to reach end-users quicker. However, we need to avoid using harsh organic chemicals, or it would defeat our aim to provide a green synthesis of valerolactam.