Safety

Laboratory Safety

To ensure experimental safety, before commencing formal experiments, our team underwent systematic laboratory safety training at the beginning of the project. We learned essential skills such as the correct use of laboratory equipment, Biosafety Level 1 (BSL-1) operating procedures, aseptic techniques, and measures to prevent biological contamination.

During the experiments, we strictly adhered to laboratory regulations, ensuring all operations complied with relevant guidelines, and underwent regular safety inspections. In the initial phase, we always arranged for at least two team members to conduct experiments together for mutual supervision. Additionally, we maintained detailed daily lab records. As the experimental procedures progressed, the team meticulously documented each step and potential risk points to ensure the scientific accuracy of both experimental design and execution.

Project Safety

The goal of our project is to develop a product that delivers whitening and anti-aging peptides, with potential applications in medical and cosmetic fields. Therefore, safety and harmlessness were key considerations in our biological design.

First, in bacterial strain selection， we chose E. coli*BL21—a BSL-1 compliant strain that does not form spores, lacks invasiveness, and poses no long-term environmental risks. To further minimize endotoxin concerns, we opted for ClearColi BL21(DE3), a modified strain with eight lipopolysaccharide (LPS) synthesis genes deleted, ensuring extremely low endotoxin levels.

Second, in the experimental design, we introduced a suicide switch based on the pBAD30 plasmid backbone, which is arabinose-inducible. This plasmid carries T4 phage-derived genes encoding endolysin and holin. Upon induction:

• Holin forms pores in the cell membrane, allowing endolysin to translocate to the periplasmic space.
• Endolysin hydrolyzes peptidoglycan in the host cell wall, compromising its structural integrity.
• The cell lyses due to osmotic pressure, releasing intracellular contents.

lysis, preventing horizontal gene transfer, limiting uncontrolled proliferation of engineered strains, and ensuring biocontainment.

Notes

BSL-1 is the standard abbreviation for Biosafety Level 1.