HKUST 2025 iGEM Team Slupeer prioritizes the safety of both laboratory and project by strictly following the Hong Kong regulations. Firstly, each iGEM team member is dedicated to completing the comprehensive safety training: how to work in a laboratory, how to properly handle the instruments, and how to dispose of hazardous materials without creating secondary pollution. Additionally, we conducted our project in collaboration with our supervisors and advisors to make every effort to ensure that the entire project was carried out as safely as possible.

Before we started the experiments, the main possible risks were identified. From the assessment, two risks were concerned, which were:

• Bacteria: Escherichia. coli ( E. coli ) strain BL21, E. coli strain BL21-CodonPlus (DE3), E. coli strain Rosetta, and Pseudomonas putida ( P. putida ) strain KT2440.
• Heavy metal: cadmium.

In order to avoid these risks, we first contacted our university’s Health, Safety, and Environment Office (HSEO) to learn what is the proper management and disposal of laboratory materials containing bacteria and heavy metals. Then the safety protocols were incorporated into our lab.

Most of our experiments were conducted in HKUST Innolab (Biosafety Level 2), which is equipped with the following safety equipment:

• Biosafety Cabinet
• Chemical Fume Hood
• First Aid Kit
• Fire Extinguisher
• Flame Retardant Benches
• Spill Kits

The Innolab is also within close range of a safety shower and eyewash station. Students operating in the laboratory are under constant supervision by qualified advisors and our team PI.

Cadmium solution

Students wore masks, buttoned-up lab coats, and gloves while working in the chemical fume hood. A waste container labelled for cadmium disposal was prepared. All remaining solutions containing cadmium were disposed of in this waste container. At the end of the experiments, the waste container was sent to the Health, Safety, and Environment Office (HSEO) for proper disposal management.

Biohazards

A trash bin lined with an autoclavable plastic bag was prepared, and all materials and lab consumables used during the experiment were disposed of in this bin. The waste was then autoclaved and disposed of by HSEO.

Bacterial Handling

The bacterial strains we used – E. coli and P. putida – are both white-listed and classified under Biosafety Level 1. Students were required to label all agar plates and consumables containing bacteria, with bacterial strain, plasmid contained, date prepared, and the name of the person-in-charge. Gloves were worn at all times, and 70% alcohol spray was prepared to wipe down surfaces before and after experiments to keep the environment aseptic. Bacteria were also disposed of only in the biohazard trash bin.

A wet lab tutorial was set up to train students on the equipment in Innolab before working on the experiments. Each member working in the lab also completed the safety courses and obtained certifications under the labels of: MC03 (Chemical Safety II / Hazardous Waste Management), MC06 (Biological Safety), and MC07 (Chemical Safety I / Chemical Safety for Laboratory Users), provided by HSEO. Students also attended workshops and tutorials before using ICP-OES machines, imaging machines, and plate readers.

In considering the future real-life applications of our project, we prioritized biosafety by integrating a robust kill switch (BBa_25CTXIKQ) into our chassis. Because the sludge treatment process requires citric acid, in the event of unintended release or leakage of engineered chassis, the absence of citrate would induce bacterial lysis, effectively preventing potential environmental hazards.