After preliminary research, we developed a goal to design a cell surface system to express PETase and MHETase, thus increasing the efficiency of PET degradation and recycling. This would in turn be extremely beneficial for the environment. To achieve this goal, we created a 2-way dialogue with the community and professionals from different backgrounds in order to improve our project.
Integrated Human Practices Map Overview
Community
1. Questionnaire
We designed and shared a questionnaire online and onsite to get to know people's perception about PET recycling and their attitude towards biological PET degradation.
Left: Questionnaire poster(online); Right: onsite questionnaire collection at member’s residency
A total of 2326 responses were collected. These responses included participants from a wide range of backgrounds and thus made the results convincing and reliable.
In favor of plastic recycling, 85.86% of the population expressed an opinion. Chemical methods still possess processing advantages and already have a more complete processing system compared to biodegradation methods, which goes to show that chemical methods are far more widespread among recycling methods. In light of the recent popularity of the biological method, we plan to study its application. The method has just been proposed and is supported by many people, suggesting that there is certainly application potential.
A comprehensive analysis of the recyclable potential of biodegradable plastics has been conducted. A majority of respondents (83.83%) support biodegradable recycled plastics, but only 81.6% said they would buy them, with 41.62% saying that their answer would depend on a wide range of factors.
Although plastics have proven to be safe and pure, there are still certain issues with chemical and physical recycling. Plastics resulting from physical and chemical recycling tend to perform poorer and have diminished quality/purity. This, however, is not the case for PET as it is degraded into its original small molecule monomer raw materials after multiple recycling cycles, instead of merely changing from one form of polymer plastic to another.
Likewise, the results of the survey strongly support our position. The public is willing to buy PET plastic products manufactured using the biological method 77.52 percent of the time. This increases our confidence of the market potential of the commercialization of bio-degraded recycled plastics.
2. Feedback on our project
From the interview, we found that bio degradation as a new method was not known by a lot of people, even for those who have heard or learnt about the concept have concerns and questions. As such, we decided to use a variety of different medias to conduct more public education programs. These programs targeted different groups regarding PET recycling using bio degradation methods.
Governors and Industries
1. Interview with Mr. Lu, Deputy Director of Wuxi Municipal Bureau of Ecology and Environment
When it comes to pollution, the country places a great deal of emphasis on water and air quality. PET for bottles is used extensively in the country. In China, that number has risen to almost 10 million tons. As part of the vision of carbon neutrality, plastic recycling and the use of degradable plastics are both considered as effective ways to reduce carbon emissions. The domestic consumption of PET bottles in China reached 5.75 million tons in 2019, accounting for 23.8% of global consumption. In the short term, PET plastics are hard to replace due to their high use and stability. The efficiency of PET recycling is important in China’s sustainable development strategy.
Feedback on our project
Our aim to utilize enzymatic degradation of PET to directly obtain synthetic raw materials has practical value and fits the national policy, the data mentioned has become part of our research data and were used in presentation slides when doing public education.
2. Interview with Flyco: Mr. Guangzhan Zhao, tech officer
Interview with Mr. Guangzhan Zhao via Tencent Meeting.
In our interview with Mr. Zhao, we proposed questions concerning the usage amount of PET plastic in product production and packaging stages. Mr. Zhao told us that they would barely use PET plastics in their products and packaging (excluding plastic bags). They would produce around 7-8million plastic bags per year.
Feedback on our project
Through our interview with Mr. Zhao, we had a better understanding of the properties of PET and did more research about the main application fields of PET. This led us to deciding on focusing on PET drink bottles.
3. Lanzhou JIN TU DI Plastic Co., Ltd. (with DUT-CHINA and CPU-CHINA)
It is honor for us to communicate with this company’s chief manager Mrs. Sun and her student Qi Liu about the current industry situation related to plastic and corresponding national manage laws.
After we presented the project brief, Mrs. Sun and Qi Liu kindly shared us with some cooperation examples they did with other companies and pointed out that in order to achieve the required product properties suitable for specific environments/purposes, they would add various additives.
Mrs. Sun then advised that we should do more research to understand the components and purification of the plastic products we would process. With additives, we might need to consider the potential residues and procedures required to isolate them.
Feedback on our project
We assumemd that after basic sorting and washing, we would get pure PET plastics to process, so with PETase and MHETase, we could degrade PET into TPA and EG as raw materials for new bottles (the recycled raw materials will function the same as newly bought ones). Thanks to Mrs. Sun’s kind reminder, we did more research and confirmed with Qi Liu that if our project target would be bottle grade PET, under most cases it would be 100% pure PET. As a result, we do not need to think too much about further isolation.
4. Interview with Dr. Jinyong Wang, Tech Manager, Transportation & Industrial Department, DuPont
In our interview with Dr. Wang, we consulted him on local laws and regulations about plastic recycling to add into our proposed implementation, as it would make it more realistic.
Besides giving us a valuable list of relevant laws and regulations to get started with (which we have shared in the CONTRIBUTION page), Dr. Wang also gave us a detailed presentation on the classification of PET plastics, its main applicable fields, different methods of PET recycling, their pros and cons and process examples.
Feedback on our project:
The presentation about PET by Dr. Wang is very complete and easy to understand, we implemented the structure to several mini lectures and got better feedback from the audiences.
Professors
1. Interview with Professor Xuhui Zhang，Jiangnan University-School of Chemical and Material Engineering
Interview with Professor Xuhui Zhang. (From left to right: Yun Cao, Professor Xuhui Zhang, Jiachang Zhang, Zirui Zhu)
In our interview with Professor Zhang, we discussed about the following questions:
-- the pros and cons of the mainstream plastic degradation methods
-- prospects of biodegradable plastics and its problems
-- trend of degradation efficiency and possibility of secondary source of pollution
-- common methods for plastic bio-degradation and examples
-- comments and advice on our project
Professor Zhang thinks it is ambitious and beneficial for such a project to do academic and theoretical research, and some enzymes can indeed achieve the effect of faster degradation of plastics. However, there are still some problems that need to be solved in the promotion and practical application.
Firstly, the performance of secondary processing sub-plastics may be reduced. For example, many thermoplastics can be directly reprocessed and utilized, but its performance will be reduced. Because it is possible to add a lot of foundation to the PET to optimize its performance as it is not pure. As a result, the performance will automatically drop.
Secondly, since a lot of plastics must be collected in the early stage to achieve the effect of large-scale degradation of plastics, labour costs is also another concern.
2. Interview with Professor Xianzhong Chen，Vice Dean, Jiangnan University-School of bioengineering
By the time we interviewed Professor Chen, we have confirmed our key host: Candicda Tropicalis, key enzymes: PETase and MHETase and use of Surface Display System, we discussed about the following questions:
-- Insights on surface display system (SDS) and room for improvement
-- Insights on further promotion and application of plastics biodegradation
-- Conditions control of enzymes
Professor Chen proposed that using non model yeast requires effective gene editing tools, and how to effectively display enzymes is also the key. He recommended using the anchor protein of Candida tropicalis to display PETase, but how to obtain the anchor protein information from the genome and how to screen the anchor protein that can correctly display a large number of proteins is very important.
Feedback on our project
We built a MODEL to predict the anchor protein from the geome of Candida Tropicalis based on the sequence analysis of signal peptide, intermembrane structure, and glycosyl phosphatidy linositol (GPI) sites.
We screened 10221 protein amino acid sequences of genome of Candida tropicalis ATCC 2033, and have predicted 129 potential GPI-type anchor proteins.
Flowchart of GPI-anchored Protein Screening
Structure of GPI anchor protein
3. Email with Professor Wenfeng Zhou, China Agricultural University - College of Science
Email contact with Professor Wenfeng Zhou
We emailed our project description and design to Professor Wenfeng Zhou from China Agricultural University - College of Science to understand her perspectives about the commercialized value of our project.
In the email, she replied that, “The project takes plastic waste as the research object and uses biological enzyme method to degrade it. The topic selection is very innovative, the research idea is practical and feasible, and technically, it has the potential to be commercialized. If it can be successfully developed and popularized, it will have important social significance and produce huge economic benefits.”
Conferences
1. CCiC 8-- The 8th Conference of China iGEMer Community
CCiC is one of the biggest academic meetings for iGEMers all over China to exchange experiences. This year, we attended the conference held by Fudan onsite from Aug 27th-28th. The judges and other teams gave valuable advice our project, and we also offered advice and help for other iGEM teams. We got ACTIVE PARTICIPATION AWARD. Beyond that, we have learned a lot experience from the various workshops provided.
IvyMaker-China poster (middle)
Members giving presentation on CCiC8
Active Participation Award
2. PLASTICASE CONFEDERATION
PLASTICASE CONFERDATION gathered 7 teams working on plastic related projects to join an online round table. Teams got to know each better through project presentation, found potential for collaboration and also to helped solve problem through discussion. Experts were invited to make comments and inspire the teams to promote the project.
Feedback on our project
Since these projects are all related to plastics, the judges comments all helped us to think
