SCU-China 2025

Laboratory Safety

The laboratory environment can be a hazardous place to work. Safety is a very important aspect of working in a laboratory. Our team is working in the safety level 1 lab, which is the lowest safety level and is sufficient for all our experiments. Our team is fully compliant with the safety and security rules of the iGEM competition. In order to provide a clean and safe laboratory environment for team members to conduct their research, we classified reagents and drugs, placed hazardous reagents into the special storage cabinet, and marked them for warning.

Figure 1. Classified medicine storage cabinet

Figure 2. Explosion-proof cabinet

We also periodically worked with our college's safety committee to examine our facilities. Nianhui Zhang, the PI of our team, is responsible for the biosafety of our lab. He can provide us with reliable safety guidance because he has 28 years of teaching experience. Before starting work in the lab, all team members must undergo comprehensive training in safety knowledge and experimental operation under the guidance of staff and teachers.

Figure 3. Lab bench

Figure 4. Biological safety cabinet

SCU-China TasAnchor

SCU-China 2025's project TasAnchor aims to capture and immobilize heavy-metal particles using engineered Bacillus subtilis adhered to filter media. Our chassis is designed for on-site wastewater pretreatment: bacteria bind to carriers, adsorb metal ions, and are removed together with the filter module. To minimize environmental risk, we integrate a density-dependent kill switch to ensure survival only under high-density, controlled conditions on the filter.

When deploying an engineered organism in water infrastructures, we must evaluate potential impacts on humans and the environment throughout the treatment path. Engineered B. subtilis may directly or indirectly contact the following locations and stakeholders, raising biosafety and ethical considerations:

Place	On-site filter unit / pretreatment tank	Downstream sewer & treatment plant	Receiving water / surrounding environment
Possible areas of influence	Operators handling filter cartridges; biofilm on carrier surfaces; aerosol during cartridge replacement	Wastewater, pipe biofilms, sludge line, maintenance staff; process upsets if cells detach	Aquatic organisms, sediment biota; incidental public exposure near discharge points; urban wildlife

*According to the principle of biocontainment, engineered bacteria should be designed to be inaccessible to natural water bodies.

1. Biosafety

In the TasAnchor system, engineered Bacillus subtilis is strictly confined within a sealed filtration device—composed of the adsorption filter, detection filter, and optical signal detection module—forming a closed-loop wastewater treatment unit that is physically isolated from the natural environment.

Since the engineered bacteria are immobilized on polystyrene fillers (6 mm), they remain fixed within the adsorption module. Even during high flow rates or backwashing, the majority of cells stay bound to fillers. When detachment occurs, the bacteria enter a low-density environment that triggers the built-in density-dependent suicide system, ensuring that escaped cells cannot survive outside the reactor.

2. Biocontainment

Operators handling wastewater or filters are protected by industrial safety regulations, including sealed filter modules, PPE, and automated sampling ports, preventing direct contact with the engineered microorganisms.

The hardware structure itself acts as a physical containment system, composed of three modules: the adsorption filter, detection filter, and optical signal detection module. These units are connected through closed aeration and liquid pipelines. The optical module automatically controls two normally open and two normally closed solenoid valves, switching the system between wastewater-treatment and backwash-recovery states. The adsorption and detection filters are assembled as an integrated unit, both aerated by an external air pump to maintain aerobic conditions for Bacillus subtilis.

We combine the closed circulation, automated valve control, and centralized recovery, ensuring that engineered cells remain confined within the device throughout their life cycle.

3. Pollution and Use of Natural Resources

The Bacillus subtilis chassis used in TasAnchor is non-pathogenic and widely recognized as Biosafety Level 1.

Within the system, the adsorption filter captures Cd²⁺ ions, while the optical signal detection module detects the red fluorescence and triggers hardware feedback.

The process consumes minimal energy—only a small air pump and control circuit—and does not introduce any chemical reagents other than the weak acidic eluent (pH 4) used for regeneration.

All metal-containing eluates are collected in closed recovery containers and can be reused after proper chemical treatment, avoiding secondary pollution. Because the filters are sealed and aerated internally, no bioaerosols, spores, or engineered bacteria are released to the environment.

The wastewater parameters (pH 6-9, oxygen concentration, nutrient level) are compatible with both microbial performance and industrial treatment standards, ensuring that the TasAnchor operation does not interfere with existing wastewater processes.

4. Socio-economic Impacts

The TasAnchor system integrates synthetic-biology innovation with industrial wastewater hardware, offering an economical and sustainable method for heavy-metal removal and recovery.

The use of Bacillus subtilis—a safe, food-grade microorganism—significantly reduces production and maintenance costs. The modular hardware, consisting of compact filters and an automatic optical control system, supports scalable deployment and simple maintenance.

During human-practice interactions, our team consulted experts and environmental-engineering companies (including Sichuan University Environmental Engineering Department, Qinghe Tech, and Meifute Environmental Group) to evaluate corrosion resistance, filler recyclability, and sludge disinfection. Their feedback was incorporated into the device design, ensuring industrial safety and compliance.