Team:BHSF ND/Description

Safety

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1. Description
2. Inspiration
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Description:

WHY?

Genetically engineered bacteria in science and industry bears the risk of intended stolen and unintended release to the environment.

WHO？

Our main project focuses on the factory and aims to solve the issue of intellectual property caused by the stealing in the factory.

WHERE?

The difference between the current factory condition and the outside environment after stealing gave us a clue. Since the outside environment is colder than factory condition, therefore our gene circuit starts with the input of lower temperature. We utilize this difference to design our project further.

WHAT?

Our project is to digitalizing a bistable module enables conditional suicide of engineered bacteria.

HOW?

To solve this problem, our team designed a digitalizing bistable module that could detect and prevent the stealing or release of engineering bacteria from labs or factories. We utilized the mutual bistable module that enabled the conditional suicide of engineered bacteria. To make it better function, we used a sensor to sense the change of external environment, a recombinase as a flip to form memory which could record the action of stealing or release, and DNase/toxic protein to decompose the functioning bacteria.

Inspiration：

A microbial drug factory stole the research and development secrets of another pharmaceutical company, applied for patents in advance, and seized the opportunity to enter the pharmaceutical market. This theft of the news directly led to unfair competition for companies that received a large number of illegal profits, and companies that were seriously researched and developed did not receive the compensation they deserved. This news caused a debate on my team. Some believe that in the current capital market, competition is inevitable, and any way to achieve the ultimate success is acceptable. Others accuse that laws fail to guarantee fair competition, that factories have no awareness of patent protection, and that companies have no practical way to protect their strains.

In the era of innovation, we believe the problem of intellectual property has to be solved. In the context of rapid economic growth, commercial competition is inevitable and can help the market to choose the most optimal solution, but to ensure fair competition, the public, the government, and the factory all need to make effective changes. The most urgent issue is the factory’s inability to protect their hard work.

After our investigation, most of the factories work hard on the management system and physical instruments, but the microbes themselves are ignored. Any sound security system or high-tech devices may have loopholes. Those rival companies with illegal competition may follow this loophole to steal microbial secrets developed by the company, yet the evidence is hard. So how to improve the microbes themselves to prevent the stealing?

After our discussions and brainstorming, we found that we could use environment change to trigger a process. Most of the time, the microbes are safe and being the process in the factory, but, while stealing, the bacteria would leave the exited culture condition. This difference gives us a clue to develop a system that reacts to the change. We want the condition in the factory to be a constant signal that tells the microbe, “ you are safe,” whereas, when someone steals the bacterium, the signal is gone, and a suicide process can be committed. We have a debate on whether the difference starts a new reaction or an inhibited reaction is function. Considering the easiness of the concept that the absence of signal causes the lack of inhibition, we try to design a suicide module that is inhibited in the factory condition and start after stealing. To do this, we use recombinase that acts as an irreversible switch. Before being processed, there is no signal, and the switch is off. When it is cultured in the factory, the switch is on, but the signal inhibits the suicide process. In contrast, when the microbes are stolen to the outside environment, the inhibiting signal is gone, and the suicide program starts.

Finding gene fragments that decompose microbes is relatively easy, but because of the uncertainty of biological leakage, any unexpected leakage can lead to false suicides signal to the active bacteria. Resolving the leak of gene expression has become a problem that has long plagued us. The existing solutions have focused on enhancing the efficiency of promoter expression. Let the promoter be as low as possible when there is no signal (but not equal to zero expression), great speed when there is a signal. This also applies to a valid terminator. So how do you prevent leak prevention? Is it possible to use a biological means to guarantee zero leakage?

After extensive literature reading and intense discussions with experts and instructors, we design a biological bistable module. The module uses mutual inhibition of gene fragments to ensure that a constant and strong signal is always inhibited on the promoter of the toxin. In this case, a slight leakage cannot change the state of suppression. In contrast, only a real input signal caused by the environmental change can balance the inhibition and further started the expression of the toxin.

Generally, after putting into the working condition, the recombinase is switched, and the suicide module is prepared. In working condition, bacteria functions, and the potential damage of leakage is prevented by the mutual inhibition of the bistable module. However, an external change after the stealing removes the inhibition; also, due to the switch initially caused by the recombinase, the expression of the toxin destroys the engineered bacteria.

Our digitalized bistable module creates a “0”state for the circuit that prevents the unexpected leakage. This design can be effectively used for future iGEM project and similar approach.