Guided by the principles of “local people solving local problems” and “tackling global challenges”, we proposed a project by incorporating knowledge of synthetic biology to solve a problem of direct concern to us.
One of our team members’ hometown is in Northeastern China. There, local residents are extremely worried about the construction of a new copper smelting factory due to fear of heavy metal pollution. We decided to learn more about heavy metal pollution and environmental governance to see what we can do to help tackle this problem.
Through extensive background research, we found that heavy metals had long been a core concern to the world. Heavy metal pollution has two characteristics: having a wide range of sources, and potentially causing detrimental effects on the human body. [1] On one hand, heavy metal pollution could be produced from various sources, such as smelting, mining, combustion, etc., which are very common in China, [2] thus increasing the risk of heavy metal exposure. On the other hand, heavy metals can also cause various diseases in humans, and many are carcinogenic as well. [3-4] Their chemical properties cause their severe toxicity and capability to induce diseases in ways such as the generation of free radicals, sabotage of DNA, disruption of ion transport, inhibition of enzymes, etc. [5] The two factors added together amount to a time bomb, ready to “explode” any time and cause severe public health incidents.
After some interviews with the local people and related experts, we found that the state has issued many relevant laws and regulations to prevent, control, and govern heavy metal pollution. Periodical environmental sampling and testing are mandatory for potentially polluting enterprises.
Through intensive interviews with industry experts, we found that conventional heavy metal detection methods also have some unmet needs. For example, the instruments and equipment with high detection accuracy are expensive, the maintenance cost is high, and the requirements for technicians are also high; For equipment that is cheap and easy to operate and maintain, in some cases, the accuracy is not satisfactory. Moreover, the most important thing is that conventional detection methods are not friendly to the environment because of the secondary pollution problem of detection residues, although heavy metal detection is supposed to be helping the environment. This is because many current approaches require digestion through chemicals such as aqua regia, therefore making the tested samples pollutive with additional pollutants such as strong acids and nitrogen oxides. Since the technicians currently have no effective and economical ways of remediation, they simply pour the samples down the drain, which may cause additional environmental pollution.
To save our environment and reduce risks to the public, we must face this question: can we invent a new pollution detection technology that is cost-effective and environment-friendly, while still accurate enough to fulfill the needs of environmental governance?
In search for a method to solve the problem, we spent a long time searching through related information to find a possible solution. Extensive literature research rewarded us with promising results: we found that synthetic biology is a rising potential solution to this problem. The specific direction we focused on is whole-cell biosensors because they can be more stable in different environments through their chassis. Numerous results have already been achieved in this direction, [6] so we decided to try to expand upon current results.
To be sure that our solution is effective and feasible, we also asked experts from environmental enterprises if they can keep and use whole-cell biosensors. The results we got are also optimistic. The experts stated that most environmental enterprises possess laboratories satisfying biosafety standards for keeping strains. One of the enterprises we interviewed was already experimenting with bioremediation through directed evolution (though synthetic biology was not involved in their research).
As for the usefulness of our project, we concluded from collected sources that the current whole-cell biosensors already exceed conventional methods in terms of cost-efficacy, efficiency, environmental friendliness, etc. However, they still lack stability and accuracy. For a new method of pollutant quantification to be approved in China, the method concerned must undergo separate characterization by several laboratories independently to cross-verify its stability and accuracy, an obstacle to further applicational development of these methods. To tackle this challenge, we found high-throughput experimentation, a rising methodology to increase efficiency. Our idea is to mutate currently existing biosensors and characterize the mutants using high-throughput experiments to improve the existing parts.
Concluding the above, we settled our project:
We applied high-throughput experimentation to improve whole-cell biosensors, constructing more accurate and stable whole-cell biosensors which can be widely approved as the next generation of pollution detection technologies to aid environmental governance and reduce the risk of heavy metal pollution.
From extensive literature research, we found a newly discovered family of genetic sequences, csoR, which are copper-sensitive. After obtaining permission from the original author [7], we decided to manufacture it into a new BioBrick and try to optimize it to produce better biosensors. According to the results gathered from our Human Practices, we decided to focus our optimization on accuracy and sensitivity. In addition, we decided to re-characterize and optimize the existing part pCusC (K1980004) as a comparison.
And our goals:
[1] Mohammed, A.S., Kapri, A., & Goel, R. (2011). “Heavy Metal Pollution: Source, Impact, and Remedies”. In Mohammed, S.K., Zaidi, A., Goel, R., & Musarrat, J. (Eds.), Biomanagement of Metal-Contaminated Soils (pp. 1-28). Springer.
[2] He, B., Yun, Z., Shi, J., & Jiang, G. (2013). “Research Progress of Heavy Metal Pollution in China: Sources, Analytical Methods, Status, and Toxicity”. Science Bulletin: 58(2), pp. 134-140.
[3] Jaishankar, M., Tseten, T., Anbalagan, N., Mathew, B.B., & Beeregowda, K.N. (2014). “Toxicity, Mechanism and Health Effects of Some Heavy Metals”. Interdisciplinary Toxicology: 7 (2), pp. 60-72.
[4] Tchounwou, P.B., Yedjou C.G., Patlolla, A.K., & Sutton, D.J. (2012). “Heavy Metal Toxicity and the Environment”. In A. Luch (Ed.), Experientia Supplementum: Vol. 101 Molecular, Clinical and Environmental Toxicology, Volume 3: Environmental Toxicology (pp. 133-164). Springer.
[5] Engwa, G.A., Ferdinand, P.U., Nwalo, F.N., & Unachukwu, M.N. (2019). “Mechanism and Health Effects of Heavy Metal Toxicity in Humans”. In O. Karcioglu and B. Arslan (Eds.), Poisoning in the Modern World - New Tricks for an Old Dog? (pp. 77-100). Intech Open.
[6] Somayaji, A., Sarkar, S., Balasubramaniam, S., & Raval, R. (2022). “Synthetic Biology Techniques to Tackle Heavy Metal Pollution and Poisoning”. Synthetic and Systems Biotechnology: 7. pp. 841-846.
[7] Hou, S., Tong, Y., Yang, H., & Feng, S. (2021). "Molecular Insights into the Copper-Sensitive Operon Repressor in Acidithiobacillus caldus". Applied and Environmental Microbiology: 87(16).