Note: this page includes both human practices and IHP! IHP is at the second half of the page.

Human Practices

Background

Microplastics, which refer to plastic particles with a diameter of less than 5 millimeters, are the primary initiator of plastic pollution. The small volume of microplastics brings up a higher specific surface area (which refers to the surface area per unit mass of porous solid substances). The larger the specific surface area, the stronger the ability to adsorb pollutants.

There are two categories of microplastics: primary microplastics and secondary microplastics. Primary microplastics refer to industrial products containing plastic particles that are discharged into the water environment through rivers, sewage treatment plants, etc., such as microplastic particles contained in cosmetics or plastic particles and resin particles used as industrial raw materials. Secondary microplastics are plastic particles formed by splitting and decomposing larger plastic waste through physical, chemical, and biological processes.

Compared with "white pollution" plastics, the harm of microplastics is reflected in their small particle diameter, which is why they pose a deeper degree of environmental harm compared to general non-degradable plastics. Human cells may also be harmed by microplastics at the level of signaling molecules, such as those involved in hormone and endocrine regulation.

Therefore, we set microplastics as the main focus of our project. We conducted a questionnaire survey to comprehend the public's awareness of microplastics and conducted expert interviews to understand the cutting-edge knowledge of microplastics.

Questionnaire

• Objective

Firstly, we sent a questionnaire survey of microplastics to examine public awareness. The interviewees were asked to answer questions about common knowledge of microplastics and their level of comprehension. In addition, this questionnaire aims to popularize the basic knowledge of microplastics—participants' level of understanding is measured by their ability to provide the correct answers to the questions. The questions directly list the microplastic facts that need attention, and participants only need to check if they understand this knowledge without providing answers. Consequently, participants can obtain the knowledge that they previously lacked. Last, we aim to raise people's awareness of microplastics and encourage them to have good living habits that reduce the environmental harm of microplastics.

• Result Analysis

The first question, 'What age are you at?' aims to know the age of each participant. The following three questions are about the level of understanding of spider silk proteins, PET enzymes, and microplastics, aiming to examine the level of knowledge through the options "very understanding," "a little understanding," and "not knowing." Among the three questions, approximately 20% of respondents answered "very well," and 35% answered, "not knowing". The result indicates that most people have a relatively limited understanding of microplastics, spider silk proteins, and PET enzymes. This conclusion is also consistent with the following results: for example, 26.25% of respondents are unaware of the origins and hazards of microplastics, and only 38.08% have received education on microplastics.



Among the 1082 respondents, only about a quarter knew about the origins and dangers of microplastics, 38% had received various education on microplastics, and about 50% knew or knew a little about how to degrade microplastics.



From the questionnaire, we can also learn about microplastics' generation, dissemination, and harm from some options. Furthermore, in terms of public support for our project, 43% of respondents opted for "support," 21% of people did not care, and others expressed their concerns perhaps they are not familiar with synthetic biology because it is a rather specialized field in their daily lives.

• Conclusion

By analyzing the survey results and estimating the degree of spread of related knowledge, our team concludes that public education (you can find this part on our education page) would be potentially helpful in increasing public awareness and comprehension of microplastics and synthetic biology.

Interview with Experts in Related Fields

Our team not only conducted the questionnaire that brought us massive persuasive data from the public, but also organized three interviews with professors and experts from Zhejiang University and Zhejiang University of Technologies.

• 1) Professor Tang from ZJUT

The first interview was with Professor Tang of Zhejiang University of Technology. As a mentor of iGEM for six years, Professor Tang from ZJUT brought up valuable suggestions and critiques during the interview in July. The iGEM team led by Professor Tang also focuses on the microplastic pollution problem. Professor Tang mentioned that our project could arouse the public's attention to environmental pollution, enhance environmental protection awareness, and hope that our two teams can contribute to solving microplastic pollution from different directions.



• 2) Dr. Chen from ZJU

At the beginning of this summer, we interviewed Dr. Chen form Zhejiang University. After introducing our project, our team members Xie Lin, Yicong and others had an in-depth communication with Dr. Chen.

Through communication with Dr. Chen, we have gained a better understanding of microplastic pollution. At the macroscopic, microplastic are carbon-based substances and have high level of pollution. Microplastic have entered human tissues and affected organs and cells including more diseases such as cancer and leukemia, also have great influence on the signaling molecular level of the entire cell and on hormone regulation as well as various aspects of endocrine. In the surroundings, the treatment of sewage also includes the treatment of microplastics. It is including but not limited to the use of physical filtration and adsorption; chemical oxidation of carbon-hydrogen bonds into alcohols and carboxylic acids, convert organic substances into gaseous such as carbon dioxide then release; The conversion of organic nitrogen into inorganic nitrogen, ammonia as well as nitrate. So microplastics can be degraded to about 60% which is better used by microorganisms and plants in the circumstances.

Dr. Chen noted the high viability of our program. In the future, as people’s understanding of microplastics is higher, relevant departments will pay more attention and more depth research, so commercial value will be higher, especially how to degrade microplastics in drinking water.

• 3) Dr. Mei from ZJU

On August 16, 2023, our iGEM team interviewed Professor Mei in the field of chemical environmental engineering at Zhejiang University. When our group brought up questions about the severity of environmental issues caused by microplastics, Dr. Mei claimed that given the limited data and research available to support the answer, there is uncertainty in this issue. Although the problems of microplastics sound terrifying because they cause the death of many marine animals, Dr. Mei claimed that humans have just realized the danger in recent years, and further research is required to identify the influence of microplastics, such as toxicity. In addition to environmental issues, Dr. Mei has extended this issue to the drinking tap water in our daily lives. She mentioned that, to his knowledge, there is no satisfactory water treatment method aimed at eliminating the harm of plastics yet, which also demonstrates the importance of plastic degradation in water treatment.



When we discussed the chemical treatment of plastics, Dr. Mei pointed out combustion, thermal decomposition, and catalytic decomposition as the three standard methods. These three methods have different drawbacks, including carbon emissions, product complexity, and the necessity for further treatment.

Dr. May also made a statement about our method, the biodegradation of plastics, recognizing that it is a method that depends on the innate and evolved immune systems of natural ecosystems, was unlikely to cause major problem for the environment and doesn’t demand additional energy input. However, the professor also noted that no such method had been put into practice at the moment, and biological plastic degradation should still be considered as a new, developing method.

All three experts gave positive opinions on our project, which made us confident that our project is valuable to the environment and society.

Summary

Through questionnaire surveys and expert interviews, we have learned that the general public does not have advanced knowledge about microplastics and synthetic biology. Hence, public education can be an effective method to improve the situation. Most people express their support for our research design. Through expert interviews, we learned about the necessity of our project and were proud to receive recognition and support from several relevant experts in the field. Our project is of great significance to the public.

Integrated Human Practices

Abstract

After preliminary research, our team decided to focus on marine microplastic pollution for our project. We attempted to harness the viscosity of spider silk to catch marine microplastics and PETase to break down microplastic by fusing the two proteins because Professor Tan's lab and we know so much about spider silk proteins. Since the summer break, we have kept up our investigation of the project while doing laboratory experiments.

Dr. Mei proposed an experiment with a physical mixture of spider silk proteins and PETase, and our team adjusted the experiment for comparison with the physical mixture. Similarly, Professor Tang, the team's leader from ZJUT-China, advised us to include a suicide system in any engineered bacteria we introduce to the ocean. Our final experimental results show that the degradation effect of lytic bacteria is better than that of precipitated proteins, which indicates that the effect of engineered bacteria in the future may be better, so we plan to design or introduce a suicide system suitable for our engineered bacteria in the next step. The conversation with Dr. Chen taught us that we may increase the amount of PETase and create biofilms to achieve the collection and breakdown of microplastics, which is our goal to be verified, may the two methods can be combined in the future.

Dr. Mei Suggests Us to Compare the Effects of Physical Mixing and Fusion

After learning about our project idea, Dr. Mei also provided opinions and suggestions on the binding project between PETase and spider silk protein. He believes that our fusion expression idea is a very good idea because microplastics are widely distributed in the ocean, and there is no doubt that collecting microplastics should be a very challenging first step in the whole process of our project.

Dr. Mei also commented and advised on the project combining PETase with spider silk protein. He acknowledged the idea and its effectiveness since microplastics are ubiquitous throughout the ocean, and the collection of waste is undoubtedly the first step throughout the process, which can be challenging and complex. Thus, adding spider silk protein would be a potential solution to the "collection" process. The professor also indicated an expectation for further examinations and noted that comparison is substantial within this process (for example, comparison with pure spider silk protein or PETase). However, the professor also expressed concerns about a few aspects. First, we need to examine the stability of our product to ensure its resistance to harsh and unpredictable conditions in the actual environment. Secondly, he was concerned about whether the product's stickiness would affect its mobility in water. He recommended comparing our product to a physical mixture of PETase and spider silk protein for our modeling section.

Seuicide System Suggested by Professor Tang

Since our experimental results show that engineered bacteria degrade microplastics better than protein, Professor Tang mentioned a series of bioengineering models with reference values. For example, she said a self-destroying system controlled by illumination conditions: bacteria, potentially engineering bacteria, can be injected with a series of DNA that can be translated into a membrane-destroying protein in an artificial blue light environment. In contrast, the bacteria still perform their expected functions under normal white light. This system is inspiring because our PETase complex will also be inputted into the actual environment in certain forms; thus, a self-destroying system allows an efficient clean-out of the outsiders we placed in the natural environment, which makes our product more environmentally friendly. Besides the suiciding system, Professor Tang also mentioned a positive-feedback promoter based on the concentration of formaldehyde and a fluorescent protein tag model that indicates the concentration of certain viruses on the macroscopic. These models are beneficial components that allow us to engineer more complicated systems in the future.

Dr. Chen Suggested Making Biofilm

Dr. Chen said we need to increase the amount of PETase enzymes which allow the polymerization of microbes into biofilm and promote visualization to help us establish the model. Since our test results showed that the purified fusion protein was not as effective as direct bacterial lysate, we planned to design a self-killer system according to Professor Tang's suggestion.