Implementation
Background
The traditional way of dealing with PET plastic is energy-consuming and low efficiency. Hence our project aims to provide a solution to the degradation of PET plastic. Compared with conventional physical and chemical recycling methods, our PET degradation enzyme products can efficiently degrade PET plastics in a short period while increasing the extent of degradation of PET plastics and reducing the emission of greenhouse gases during the degradation process.

We established an efficient secretion system of PET degradation enzyme in Escherichia coli BL21(DE3) using signal peptide PelB and Escherichia-releasing protein Kil, which not only improved the production of the enzyme but also greatly simplified the purification process of PET degradation enzyme. In addition, we also originated from Schlegelella Brevitalea SP.nov. PET hydrolase (SbPETase) was designed reasonably, and the three mutants with higher activity were obtained by rapid screening using the established secretory system.
Target users
Our final product will be a liquid of PET enzyme, We also provide the product PTA after PET degradation, which can be used as the raw material of PET. Our product can degrade plastic efficiently and emit fewer pollutants. This enzyme can degrade PET up to 97%, with the degradation time being 10 to 16 hours, and 100% of the product can be recycled.

Our target customers include plastic manufacturers and transfer stations. We hope these factories and stations can use our company’s products to recycle and reuse wasted plastic instead of going to landfill. Our company will aim to replace competitors who supply the same kind but have low efficient enzymes. Thus, our price will be relatively higher than our competitors as our products have higher efficiency and higher recycling rate of PET plastic degradation than traditional PET degradation enzyme.
Product
Our goal is to simplify the purification process of the PET degradation enzyme and modify the PET degradation enzyme sbPETase, aiming to make PET plastic degradation more efficient. More companies will use recycled plastic by promoting our products and making it easy to degrade plastic. We will be able to reduce pollution worldwide and create an eco-friendly environment. Therefore, the company will mainly be a scientific research company divided into three production lines:
1) Authorized technology patents open the franchise.
2) The enzyme is used as raw material, processed into liquid or solid plastics to degrade chemicals, and transported to sales channels.
3) The company recycles plastic, uses the degradation of PET enzyme, converts the waste into DMT, and then gets TPA after hydrolysis, which is sold to plastic production factories as a raw material of PET plastic.
Engineering Procedure
To produce our PETase degrading enzyme, we start with PelB gene encodes signal peptide molecules to guide sbPETase protein to shuttle into the periplasmic space, and kil protein helps sbPETase secrete through the cell membrane to the outside of the cell. At last, PelB is degraded by signal peptidase in periplasmic space.
Safety and Challenges
All experimental procedures are carried out in accordance with the safety requirements of the iGEM organizing committee, and other activity pages strictly abide by local Covid-related policies. The organisms we used in the laboratory were non-toxic and non-pathogenic, all experiments were carried out on a sterile experimental bench without external contamination.

We also encountered some challenges during the project. For example, TPA which is the final product after the degradation, remained toxic. And we need to optimize the process of directed evolution. But we tried to find answers and solutions by conducting interviews with experts. In addition, TPA which is the final product after the degradation, remained a little toxic which we still need to investigate the further processing methods to deal with.
Future Plan
Based on our business plan, trying to contact organizations that may fund our project, and connect with cooperative manufacturers, to implement the commercialization of the product in reality.
Besides, we will continue our work in the laboratory to overcome those challenges and optimize our solutions.