Designing Genetic Code Lock In Escherichia Coli

With the advent of synthetic biology, excellent genetically modified microorganisms are widely used for biomedical, food, chemical engineering and energy applications, at the same time accompanied by pressing biosafety and intellectual property problems. Once released to environment, genetically modified microorganisms may bring unpredictable effects on ecological environment and technology innovation. Focused on the issues above, two kinds of flexible, functional and robust genetic code locks are successfully designed and constructed through synthetic biology and molecular biology methods to regulate cell growth artificially and further to protect microbial strains. The main research results are as follows:Cell division inhibition genes minC、minC-minD and quorum sensing system AHLLuxR are selected to construct two kinds of cell division regulation gene circuits which can effectively inhibit cell growth of Escherichia coli by 53.34% and 59.33% respectively. Acyl Homoserine Lactone molecules(AHL) are added to regulate the expression of minC、minCminD and further to finely regulate cell growth.Essential gene hemD related to cell respiratory, chaperone ipgC and transcription factor mxiE induced by arabinose and IPTG respectively are selected to construct two kinds of essential gene regulation circuits. The one is a single layered gene circuit which induces the expression of hemD directly by arabinose, the other one is a double layered “AND” gate gene circuit which induces the expression of hemD by arabinose and IPTG.The results show that strain Δhem D has a poor growth and added inducers can both activate single and double layered essential gene regulation circuits in order to control microbial growth effectively.Therefore, two kinds of gene code locks constructed are able to control cell growth and viability effectively, which has great significance in biosafety and biosecurity field. It is certain to have great significance with regard to avoiding the spread and diffusion of hazardous biological factors and it is valuable for intellectual property protection and further reduce economic losses caused by strains missing.