Antibiotics have played an important role in safeguarding human health and promoting the development of animal husbandry for a long time. However, in recent years, the overuse of antibiotics has aroused widespread concern, mainly focusing on the emerging problems of antibiotic-resistant bacteria and resistance genes. Antibiotic and antibiotic resistance genes are new pollutants, and antibiotic contamination does not accumulate in the body, 70% - 80% of antibiotics will be discharged into the environment with urine, the impact on microorganisms in the environment. Antibiotics enable microorganisms in the environment to screen resistance genes, enhance resistance, and possibly form superbacteria. Resistance genes are also likely to spread and spread in the environment, threatening public health, food and drinking water safety, thereby causing direct health hazards to our human beings.
Antibiotic resistance: Global Surveillance Report released by the World Health Organization in 2014 shows that 63,000 people die each year from super-resistant bacteria in the United States and 25,000 in the European Union. The number of deaths caused by superbugs in the United States far exceeds that of HIV infected deaths. If the global spread of superbacteria is not effectively curbed, the resulting death toll could increase by 10 million annually. To cope with the spread of superbug, the world needs to spend 100 trillion dollars by 2050. Therefore, it is necessary and urgent to carry out the related research on antibiotic resistance genes and reveal the diffusion and transmission of antibiotic resistance genes in the environment for assessing the ecological risk of antibiotic resistance genes.
Existing treatment technologies can only deal with some of the genetic contaminants that have been diffused into the environment, but can not eliminate the source of pollution from the source. Therefore, we expect to construct a controllable genetic engineering bacteria with self-eliminating ability of resistant genes by using CRISSPR/Cas9 technology with high efficiency of gene editing and optical control system, that is, to solve the problem of bacterial resistance from the source, and to provide a possible and effective way to solve the problem of resistant gene pollution and protect the ecological environment.
CRISPR/Cas is the abbreviation of Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated protein 9. CRISPR/Cas system is the immune system of prokaryotic organism, when guided by gRNA, Cas protein can cut the target DNA and cause a double-strain break. Now this system has become an efficient, fast and accurate genome editing tool.
Basically, the CRISPR/Cas9 genome editing system needs two plasmids, one expresses Cas9 protein, the other provides sgRNA which is rea human-designed gRNA. Antibiotics resistance has become a global health issue. Till today, almost all of microbiology labs and fermentation factory use antibiotics resistance gene as selective marker. Our project creates a plasmid that include both Cas9 gene and sgRNA sequence. When induced by light of a certain wave length, it cuts the antibiotics resistance genes in the bacteria preventing them from leaking into the environment.