The authors developed a biological containment system to prevent the spread of genetically modified bacteria in the environment. The system uses a combination of thymidine auxotrophy, a gene expression regulator (ER), and a CRISPR device (CD) to control gene expression and prevent the release of the genetic circuit to other bacteria. The ER consists of two components: a crRNA and a taRNA. The crRNA represses the expression of a gene of interest by blocking access to the ribosome binding site, while the taRNA exposes the RBS and initiates translation of the gene. The CD is a sequence-specific bactericidal device that induces double-strand breaks in a target DNA sequence, preventing the acquisition of essential genes from environmental bacteria and killing bacteria that harbor artificial genes. The authors tested the system in mice and found that it was highly effective in preventing the spread of the genetically modified bacteria. They also showed that the system was stable for at least 10 days in the mouse gastrointestinal tract and prevented the disruption of thymidine auxotrophy by horizontal gene transfer of the thyA gene. Overall, the authors’ biological containment system provides a promising approach for preventing the unintended spread of genetically modified microorganisms.
One-stop genetic editing and containment of a modified beneficial microbe for effective environmental stewardship
