Efficient Knocking Out of the Organophosphorus Insecticides Degradation Gene opdB in Cupriavidus nantongensis X1 T via CRISPR/ Cas9 with Red System.

Cupriavidus nantongensis X1 T is a type strain of the genus Cupriavidus , that can degrade eight kinds of organophosphorus insecticides (OPs). Conventional genetic manipulations in Cupriavidus species are time-consuming, difficult, and hard to control. The clustered regularly interspaced short palindromic repeat (CRISPR)/associated protein 9 ( Cas9 ) system has emerged as a powerful tool for genome editing applied in prokaryotes and eukaryotes due to its simplicity, efficiency, and accuracy. Here, we combined CRISPR/ Cas9 with the Red system to perform seamless genetic manipulation in the X1 T strain. Two plasmids, pACasN and pDCRH were constructed. The pACasN plasmid contained Cas9 nuclease and Red recombinase, and the pDCRH plasmid contained the dual single-guide RNA (sgRNA) of organophosphorus hydrolase ( OpdB ) in the X1 T strain. For gene editing, two plasmids were transferred to the X1 T strain and a mutant strain in which genetic recombination had taken place, resulting in the targeted deletion of opdB . The incidence of homologous recombination was over 30%. Biodegradation experiments suggested that the opdB gene was responsible for the catabolism of organophosphorus insecticides. This study was the first to use the CRISPR/ Cas9 system for gene targeting in the genus Cupriavidus , and it furthered our understanding of the process of degradation of organophosphorus insecticides in the X1 T strain.