. Safety .

1. Safe Project Design

Great importance is attached to safety in our project design. In molecular experiments, we engineer E. coli which poses no threat to individuals or the environment. E. coli DH10β, DH5α, BL21(DE3), and Nissle 1917 are applied as the chassis organisms when we implement the experiments of characterization and expression.

This year our team fight for anti-icing and anti-drought solutions. In the frost prevention part, we engineer E. coli DH10β to express and secrete antifreeze proteins TmAFP and SfIBP which can lower the freezing point of water in rhizospheric soil and inhibit ice crystal recrystallization. And in the drought resistance part, we engineer E. coli Nissle 1917 and BL21(DE3) to produce harmless water-retaining material bacterial cellulose (BC)/hyaluronic acid (HA) complex. We design an almost hermetic bioreactor in which we could store and maintain our chassis out of contamination and only release the product from it to the soil, reducing the possibility of bacteria diffusion in the environment.

All the proteins are totally harmless to the human body. All the plasmids are harmless for human beings and none of our parts would raise any safety issue according to the current expertise.

Other than that, since we choose soil as the target, putting the "effector" into the natural environment is inevitable. Considering further biosafety, we apply corresponding kill switches to avoid the potential leakage of engineered bacteria and design a toxin-antitoxin system to prevent horizontal gene transfer.

2. Safe Lab Work

The laboratory is equipped with the location of emergency exits, emergency ventilation devices, fire-fighting equipment, first aid kits, and so on. Every year after recruiting new members, we spend several weeks training them in basic laboratory operations and handling safety accidents. When entering the laboratory, we must wear laboratory clothes, gloves, and goggles. All bacterial culture mediums have undergone sterilization treatment. We strictly follow the BSL-1 regulations to dispose of all biological materials and metabolic waste. The laboratory is also equipped with specialized operators for handling hazardous materials and biological products.

Fig. 1 The first aid kits for our lab

At the same time, we invited laboratory safety engineer, Lina Wu, to conduct safety education for all team members when they officially got into the experimental phase.

Fig. 2 The safety training for team members