To enhance the biosafety of engineered bacteria, we designed a controllable suicide system based on the arabinose-inducible promoter PBAD, which drives the expression of the E. coli endogenous toxin MazF (BBa_K1096002), enabling precise regulation of bacterial growth.

Experimental results showed that under L-arabinose induction, the growth of DH5α-PBAD-MazF engineered bacteria was significantly inhibited, whereas the non-induced group and wild-type controls grew normally. This demonstrates that the system can function as a controllable “suicide switch” for biosafety control under arabinose induction.

Additionally, in space environments, cosmic radiation poses a threat to both plants and microorganisms. Researchers mitigate this by using shielding from spacecraft walls, water-layer composite shielding, and leveraging the organism’s intrinsic antioxidant systems and DNA repair mechanisms to maintain stability.

Based on this, we encapsulated lyophilized probiotic powder into thin-film microcapsules suspended in liquid. This design not only makes it convenient for astronauts to consume but also partially protects the bacterial strains from radiation exposure.

To prevent potential side effects from engineered bacteria and their products in vivo, or to allow users to promptly halt bacterial activity, we designed a controllable suicide system based on the arabinose-inducible promoter PBAD.

This system drives the expression of the E. coli endogenous toxin MazF (BBa_K1096002), enabling precise regulation of engineered bacterial growth, thereby enhancing the safety of the bacteria during application (Figure 1).

Figure 1. Functional Validation of the Arabinose-Inducible Promoter

Experimental results showed that under L-arabinose induction, the growth of the engineered strain DH5α-PBAD-MazF was significantly inhibited, whereas the non-induced group and wild-type controls exhibited no noticeable growth changes.

These findings indicate that the PBAD-MazF system can effectively activate toxin expression upon arabinose induction, thereby suppressing host bacterial growth. This validates its feasibility as a controllable “suicide switch” for biosafety control in synthetic biology applications.

Figure 2. Validation of the Suicide System

In summary, to prevent potential side effects from engineered bacteria and their products in vivo, or to allow users to promptly terminate bacterial activity, we designed a controllable safety system.

This system utilizes the arabinose-inducible promoter PBAD to drive the expression of the E. coli toxin MazF (BBa_K1096002), enabling self-lysis of engineered bacteria in the presence of arabinose.

Figure 3. Discussion with Dr. Deng

From our discussion with Dr. Deng, we learned that in space environments, cosmic radiation poses serious threats to plants and microorganisms. High-energy particles and ionizing radiation can damage DNA, induce mutations, inhibit growth, and even cause cell death, thereby jeopardizing the stability of space ecosystems.

To mitigate these effects, researchers implement multiple protective strategies:

• Physical shielding: Adding polyethylene, aluminum alloys, or water layers in spacecraft walls and plant cultivation modules to reduce radiation intensity.
• Biological protection: Utilizing plant antioxidant systems and microbial DNA repair mechanisms to enhance self-protection.
• Genetic engineering: Screening or engineering radiation-resistant strains to maintain stable biological functions during long-duration missions.

Among these measures, water, rich in hydrogen atoms, is considered a key resource providing both life support and radiation shielding. Water layers can effectively attenuate cosmic rays and high-energy solar particles, reducing DNA damage in plants and microorganisms. Properly arranged water tanks also integrate drinking, recycling, and radiation protection functions. In plant growth chambers and microbial modules, surrounding water layers significantly lower mutation rates, maintaining normal metabolism and reproduction.

Furthermore, combining water with polyethylene and aluminum alloys forms a composite shielding system, improving overall protection efficiency while optimizing resource utilization. Therefore, water serves as a dual-purpose resource–shield material, playing an indispensable role in biological support and ecosystem construction for future deep-space exploration.

Based on these insights, our product adopts a unique design: freeze-dried probiotic powder is encapsulated in thin-film microcapsules and suspended in liquid. This design not only facilitates astronaut consumption in space but also partially protects the bacterial strains from radiation-induced mutations and unpredictable effects (Figure 4).

Figure 4. Product Design Scheme

This project successfully characterized the function of MazF protein and constructed a controllable suicide system, achieving precise regulation of engineered bacterial growth. This provides a reliable module for biosafety in synthetic biology.

Additionally, combined with space radiation protection strategies, we proposed an innovative packaging design for freeze-dried probiotic powder, offering a reference for future deep-space biological support and stability of space ecosystems.

These achievements not only enhance the safety of engineered bacterial applications, but also provide iGEM teams and future research projects with directly applicable biosafety strategies and space adaptation solutions.