Riverbanks, lakesides and beaches, these supposedly picturesque places, are now covered by plastic waste. These carelessly discarded plastic bottles, bags and food packaging not only destroy the harmonious beauty of nature, but also pose a huge threat to aquatic life. With the rapid development of industrialization and modern life, plastic products have penetrated deeply into people's daily lives. However, the extensive use and careless disposal of plastics has led to an increasingly serious environmental problem: microplastic pollution. Microplastics, as a substance that is difficult to decompose, accumulate in water bodies for a long time, causing direct harm to the organisms in them. Many aquatic organisms mistakenly eat these microplastic particles, affecting their growth and development. What’s more serious is that these microplastics accumulate step by step in the food chain and may eventually return to the human table, causing potential harm to human health.

Microplastics are widely defined as plastic particles with a particle size less than 5 mm, which are widely found in water, soil and living organisms. The earliest research on microplastics can be traced back to 2014. Research by Richard Thompson, director of the International Marine Debris Research Center at the University of Plymouth, and others found that plastics and fibers with small particle sizes are widely present in the ocean, and they are transferred with the flow of seawater. The 2014 Yearbook released by the United Nations Environment Program officially listed microplastics as one of the top ten emerging environmental issues in the world. Microplastics have received increasing attention as an emerging issue of environmental pollution.

In order to make our project go smoothly, our team visited the aquarium, visited the person in charge of the tourist attraction and the fishermen, and learned the relevant knowledge and response methods; interviewed experts in the field and fishermen to ensure that our plan was feasible , and can really help people; go to different places to conduct discussions and popularize science, so that people can understand relevant knowledge, promote our products, and obtain certain feedback and suggestions.

Our inspiration came from visiting the aquarium. During our visit, our instructor, Mr. Chen, taught us that the number of marine species has dropped sharply this year, and marine life has also been greatly reduced. The reason is that the environment in the ocean is getting worse. Among marine pollution, one of the relatively easy-to-understand types of pollution is undoubtedly plastic products that are inseparable from our daily lives. "Plastics float on the sea, hide in the water, and are everywhere." Teacher Chen said. Plastic pollutes the sea and poisons life in the ocean. Some plastic products restrict the activities of marine life and cause their death.

In order to gain a deeper understanding of our topic and carry out relevant research, our team first went to the Yangtze River in Wuhan for on-the-spot investigation and observed garbage of various sizes and shapes floating on the sea, including many plastic products. Most of the garbage is: plastic cans, plastic bags, foam boxes, etc. These are commonly used items in our daily lives. Perhaps due to careless throwing or improper handling, they appear in the water where they should not appear. We conducted random interviews with people walking and fishing along the river: "If the highest level is level 10, what level do you think the current severity of microplastic pollution in the water is?" Almost everyone thinks the current severity is level 9 or 10. Level, "It's terrible. Plastic can be seen everywhere. There are always news about aquatic creatures being entangled and suffocated by plastic garbage, or dying from eating plastic garbage," everyone said. However, there are also a very small number of people who think that the current pollution is not serious or has nothing to do with them. "Microplastics are in the water. As long as I don't eat aquatic organisms, the microplastics will not enter my body," a passerby said.

Through the results of this survey, we found that the majority of people believe that it is urgent to deal with microplastic pollution. Therefore, our topic is worthy of in-depth study. If a method of biodegrading PET can be discovered, it will surely make a contribution to improving the water environment. certain contribution.

We collected data online, and at the same time went to professional research institutions to study. We analyzed the usage rates of various methods for degrading PET. We found that currently physical degradation and chemical degradation are the main ones, with photodegradation and biodegradation being the main ones. The frequency of use is low. Among these four methods, the usage rate of biodegradation is the lowest. For the other three methods, we have a certain understanding and we learned that:

Chemical degradation – Converting microplastics into smaller molecules such as formaldehyde and benzene through chemical reactions, such as the use of enzymes. The disadvantage of this approach is that the resulting substances may still be toxic.

Physical degradation – using high-pressure water or ultrasonic vibrations is used to break down microplastics into smaller pieces, but it only reduces the size of the problem rather than actually solving it.

Photocatalytic degradation - using specific photocatalysts to decompose microplastics through light reactions. While this method works for some plastic types, it's not a universal solution.

The above three methods all have disadvantages to a certain extent, so we focus on the fourth method: biodegradation.

This method harnesses the natural ability of microorganisms such as bacteria, fungi and algae to break down plastic into environmentally friendly substances such as biomacromolecules, carbon dioxide and water. In this regard, we interviewed the person in charge of the scenic spot about their acceptance of the biodegradation method. Out of a perfect score of 10, 78% of the person in charge gave it a score of 9, and 20% said they disagreed. Yes, give a score of 1. Two percent of the people in charge said they were not concerned about microplastic pollution. It can be seen from the survey results that most scenic spot managers need an emerging method to solve the problem of microplastic pollution.

Although biodegradable microplastics currently face difficulties such as the efficiency needs to be improved and people are not optimistic about it, it provides an environmentally friendly and sustainable treatment method. We hope that with the continuous deepening of scientific research, more efficient biodegradation strategies can be discovered to truly solve the global environmental problem of microplastic pollution. Our research not only represents the progress of science and technology, but also a philosophical thinking about the harmonious coexistence between human beings and nature.

When studying this topic, we have to focus on the fishermen group - fishermen are fishing. When one day the water body is polluted, their way of survival will also be cut off. If we want to help them, we first need to understand their needs. Therefore, we interviewed many fishermen to hear their concerns. One of the fishermen, Li Changsheng, lamented: "A few decades ago, there was not so much garbage on the sea. At that time, the water surface was very clean. There was no need to worry about pollution problems. The water was also crystal clear and the fish grew fat and strong. , It’s different now, it’s very dirty!” After we briefly explained our idea to Master Li, Master Li said that as long as it can effectively solve the problem of marine microplastic pollution, he will support it wholeheartedly, “I miss the past a little bit The river is extremely clear. I hope the microplastic pollution will be solved soon."

We also interviewed another fisherman, Jiang Jun. Master Jiang said: Due to the serious pollution of microplastics, the current sales of aquatic products are bleak, and it is beginning to be a little insufficient to make a living. "I have been fishing with my family since I was very young. Now I don’t know what other ways to survive," Master Jiang sighed.

After conducting some preliminary investigations, our team believes that microplastic pollution is an urgent issue that needs to be dealt with. The most obvious ones are the interests of fishermen and scenic spot managers. In the long run, if microplastic pollution continues, then all Humanity will be affected. Therefore, we contacted Dr. Qiao for communication. Dr. Qiao is currently researching the corresponding field. He carefully explained to us the relevant knowledge of microplastics. The main component of microplastics is polyethylene terephthalate (PET), which is a creamy white or light gray highly crystalline polymer with a smooth and shiny surface. It has the characteristics of creep resistance, fatigue resistance, friction resistance and good dimensional stability, low wear and high hardness, little influence by temperature, and good stability. PET is mainly used in fibers, films and engineering plastics. Therefore, many items in daily life can easily cause PET pollution. We asked Dr. Qiao how to design a microplastic processor. Dr. Qiao introduced to us that in recent years, Japanese scientists have discovered a bacterial PET degrading enzyme, PETase. This enzyme can degrade PET, but its enzyme activity is low and can Poor usability. If we can find a way to exert the activity of the enzyme, we can make PETase effectively degrade PET, making this project feasible.

After receiving guidance from Dr. Qiao, we also asked students from Wuhan University for their opinions: What do you think is the ideal way to deal with PET? Many students put forward a point of view: It would be great if PET could be converted into other harmless substances. After group discussion, the first-generation gene circuit diagram was designed, which included the T7 promoter, RBS, PETase gene, and terminator. In this mode, PETase is continuously expressed to achieve the purpose of degrading PET in water. After designing it, we conducted experiments and found that our engineered bacteria could degrade PET, but the efficiency was extremely low and there was no significant degradation ability.

We found Mr. Luo from Southern University of Science and Technology for discussion. Mr. Luo pointed out: Most of PET exists outside the cells, while the PETase expressed by the engineered bacteria we designed is inside the cells. One is outside and the other is inside. The difference in relative position hinders rate of degradation. Based on Teacher Luo's suggestion, we designed the genetic circuit diagram of the second-generation microplastic processor. In the second-generation microplastic processor, we adopted a new technology - cell surface display technology. Through cell surface display technology, PETase can be displayed outside the cell and react with extracellular PET.

We used INP to display PETase on the surface of the engineered strain, and used wild-type E. coli Rosetta as a control to explore the difference in degradation capabilities between the two. The experimental results showed that the catalytic efficiency of PETase was significantly enhanced after using surface display technology.

After obtaining the above satisfactory results, we were ready to produce and put it into use. However, biosafety expert Shen Chao told us that if we want to use this strain to put it into lakes or oceans, we will face abnormal situations. Serious biosafety issues. "I believe many people are unwilling to accept that there are bacteria in the food they eat or the water they drink," Teacher Chen replied, and also strongly stated: This is against biosafety.

Later we found that the Lithuanian igem team (vilnius-lithuania) characterized a very good cellulose-binding protein in 2022, and we decided to use its part as a binding protein for bacterial cellulose-based microbial immobilization technology. ⩽. At the same time, we purchased bacterial cellulose to verify the feasibility of its fixation technology. We have designed a third-generation microplastic processor. Compared with the second-generation microplastic processor, the third-generation processor has an additional component of INP-CBD. INP-CBD will be continuously expressed in the engineered bacteria. INP can By displaying CBD on the cell surface, the engineered bacteria can be anchored to the cellulose membrane, thereby preventing the engineered bacteria from spreading in the sea and posing biological safety hazards.

After completing our lab work, we designed a hardware device that would both prevent strain leakage and improve water treatment efficiency, allowing our engineered strains to efficiently degrade plastics in open water. Our hardware equipment mainly consists of shells, buoys, water pumps, bacterial cellulose carrying engineered strains, traction ropes and anchor rods. During use, we put bacterial cellulose carrying engineered strains into the device and then put the device into the water. Buoys help the device stay afloat on the water. After connecting to the power supply, the water pump starts, drawing the upper water body (because plastic is enriched here) into the device and processing it through bacterial cellulose carrying engineered strains. The engineered bacterial strain will begin to degrade the PET, and the cleaned water will then drain out of the bottom of the device. In communicating with staff at the Wuhan East Lake Management Office, we realized that it would be impractical to provide power outlets at every location around the lake. Therefore, we added solar panels to the device so that it can operate independently and not rely on a power source. We expect this innovation will make our equipment more sustainable and suitable for a wider range of environments. These innovative designs and technologies are expected to play a key role in solving the problem of plastic pollution and make our environment cleaner and healthier.

We sent the prepared third-generation microplastic processor to the scenic spot managers and fishermen interviewed above. After they used it for a week, we conducted a questionnaire survey on the scenic spot managers and fishermen. With a full score of 5, the three scenic spot directors all gave scores of four or above. The person in charge said: “After using this set of microplastic processors, we also invited specialized monitoring personnel to detect the water in the water. The content of PET has been found to have a significant effect after use. The content of PET in the water body has been greatly reduced, which is very beneficial to our tourism industry. At the same time, it can also alleviate microplastic pollution, which is very good." Among the three fishermen, One fisherman gave a score of 1. He believed that this instrument was of little use and he was not willing to take care of the instrument every day. The other two fishermen gave higher scores. The two fishermen said: "I don't understand a lot of knowledge, but when we hear that this product can degrade plastics, we feel that the product is good for people, and we will support it. "After receiving such feedback, we realized that in addition to the practical activities we have completed so far, we must also pay attention to the popularity of microplastic pollution in the future, so that more people can understand and understand the problems behind this pollution and the seriousness of the problem. .

After a series of experiments and practices, we are confident that we have obtained an efficient, low-cost, and environmentally friendly microplastic processor. We went to the waters of Wuhan to carry out volunteer activities. While setting an example to protect the environment, we did not forget to educate passers-by about the harm of microplastics to the environment. We also called on people to use less disposable plastic products. Even if they are used, they cannot be thrown away at will. They need to be put in Designated location, waiting for professional knowledge for subsequent processing. We also set up a publicity corner to educate passers-by about the current situation of microplastic pollution, reminding people that it is urgent to protect the environment and not to take it lightly. At the same time, we also held an exchange meeting with environmental protection organizations. At the meeting, we discussed the impact of the device on the environment, the possibility of popularization of the device, the scope of application of the device, the practicality and economic effects of the device. We hope that Let more people know about such a microplastic processor, hoping that in this way, we can strengthen people's understanding of environmental protection and obtain valuable user feedback. In general, in the face of the global environmental problem of microplastics, we hope to create a more harmonious and healthy living environment for humans and nature through unremitting efforts.