Our team’s project aims to address the issue of eutrophication caused by excessive phosphate discharge into water bodies. We have developed a system based on genetically modified bacteria to recover phosphate from wastewater. The high-affinity phosphate-binding protein (PBP) selectively binds to phosphate through 12 hydrogen bonds in a deep cleft, exhibiting extreme selectivity even in the presence of structurally similar arsenate. Compared to traditional metal oxide adsorbents, PBP absorbs phosphate 30-40 times faster with an adsorption affinity 10-15 times higher, making it both environmentally friendly and safe.

The project is designed to use PBP proteins for phosphate adsorption, effectively separating phosphate from water using reusable beads, achieving the dual goals of resource recovery and pollution control. The entire system not only significantly reduces phosphate discharge but also enables the recycling of phosphate in agriculture and industry. Through advanced fermentation tank production technology, the engineered bacteria in the system ferment PBP proteins in a closed environment, ensuring that no live bacteria enter the natural environment. In both the laboratory and fermentation tank operations, we adhere to strict biosafety and environmental protection requirements to ensure the safety of experiments and real-world applications.

In the early stages of our project, we planned to use live engineered bacteria to degrade pollutants in wastewater. However, we later realized that even in semi-enclosed environments, there is still a risk of leakage. After comprehensive consideration, we adjusted our project to focus on secreting PBP proteins within a fermentation tank. As a result, only PBP proteins will be present during wastewater treatment in treatment plants, with no live engineered bacteria involved, effectively avoiding the risk of engineered bacteria leakage.

In laboratory operations, our team strictly follows safety management protocols. All members undergo detailed safety training, ensuring proficiency in the use and maintenance of personal protective equipment (PPE) such as goggles, lab coats, gloves, and face shields. Additionally, we require all personnel to strictly adhere to laboratory operating procedures to prevent accidents during experiments. For chemicals and biological materials used in the experiments, we have clear handling standards to ensure safe storage and usage, particularly for managing engineered bacteria to avoid any risks. The fermentation tank, as the core part of the system, is fully enclosed, effectively preventing any leakage risks. After fermentation, all engineered bacteria and waste are thoroughly sterilized, ensuring no live bacteria remain, thereby preventing threats to the environment and personnel. Training includes proper handling and disposal of hazardous waste, covering classification, storage, and transportation regulations to meet environmental protection and safety standards.

This project uses genetically modified E. coli to produce PBP proteins. The engineered bacteria only ferment in closed fermentation tanks, with PBP proteins extracted in secreted form and directly used in the phosphate adsorption process via beads. After fermentation, the tank undergoes thorough sterilization to ensure that no live bacteria leak into the external environment. This design ensures that engineered bacteria are only used in the production phase, and no live bacteria are present in the real-world application, avoiding potential biosafety risks. The closed nature of the fermentation tank further reduces any risk of leakage during operation. After the fermentation process, all waste bacteria and residual media are sterilized and disposed of according to biological waste management regulations, ensuring no environmental pollution occurs.

Our team has implemented several environmental safety measures. By efficiently adsorbing and recovering phosphate from wastewater, we reduce the risk of eutrophication in water bodies. We use reusable adsorption beads that can repeatedly adsorb phosphate and be cleaned for reuse, reducing resource waste during experiments and further enhancing the system’s environmental friendliness. Compared to traditional magnetic beads, these adsorption beads are equally reusable but better suited to our project’s processes, ensuring both operational safety and reduced resource consumption. Additionally, we strictly manage hazardous waste generated during experiments and production, with all waste being classified, stored, transported, and treated in accordance with environmental protection regulations.

To ensure safety throughout the application process, our team has conducted a detailed risk assessment for each step and developed emergency response plans. In practice, the closed design of the fermentation tank effectively controls the risk of bacterial leakage. Even in the event of equipment failure, emergency shutdown and sterilization procedures will be immediately initiated, ensuring no threat to the environment or personnel. The risk of engineered bacteria leakage is controlled through multiple layers of safety design, including the tank’s sealing, regular equipment inspections, and strict operating procedures. After fermentation, all contents are thoroughly sterilized, ensuring no live bacteria remain. Furthermore, the adsorption beads can be reused after cleaning, and we have assessed their chemical properties and operational safety to ensure that no harmful substances are generated during use and recovery, minimizing potential environmental threats.

Teachers provide us with laboratory safety education, teaching us about the types of personal protective equipment (PPE) such as goggles, lab coats, gloves, and face shields. We learn how to select and use the appropriate PPE to prevent chemical, biological, or physical injuries. Laboratory behavioral norms are also taught, including the prohibition of eating and drinking, adherence to laboratory rules, and maintaining a clean workspace.

Team members regularly undergo safety training to ensure familiarity with experimental protocols, proper use of PPE, and hazardous waste classification and disposal. Each team member receives detailed training on laboratory and fermentation tank procedures, and emergency response plans are practiced to ensure any incidents are promptly addressed. The team strictly follows iGEM biosafety and laboratory standards, ensuring that all experimental designs and engineered bacteria handling methods comply with biosafety regulations. Additionally, the team conducts regular internal audits to ensure that all processes are carried out according to safety protocols, with safety assessment reports submitted to the iGEM Safety Committee.

Looking ahead, we plan to further optimize the performance of the engineered bacteria and adsorption beads to improve system stability and adsorption efficiency. By enhancing fermentation tank and adsorption technology, the system will be able to handle a broader range of wastewater types, such as household and industrial wastewater, thereby expanding its scope of application. We will also continue to explore ways to improve the material quality of the adsorption beads, further reducing costs and improving phosphate recovery efficiency. Moreover, the team will actively collaborate with other research institutions and industries to promote the application of phosphate recovery technology and contribute to the development of relevant policies, advancing the sustainable use of phosphate resources globally.