CRISPR is a repeating sequence in the prokaryotic genome. It is an immune weapon produced by the struggle between bacteria and viruses in the history of life evolution. Simply put, the virus can integrate its own genes into the bacterial genome and use the bacterial cell tools for its own the gene duplication service. In order to remove the foreign invading genes of the virus, Bacteria evolved the CRISPR-Cas9 system. With this system, bacteria can quietly remove the virus gene from its own chromosome, which is the unique immune system of bacteria. Microbiologists have mastered the immune function of bacteria with a variety of excised foreign virus genes. The more…