First genome transplant performed

For the first time, scientists have completely transformed a species of bacteria into another species by transplanting its complete set of DNA. The achievement marks a significant step toward the construction of synthetic life, with applications including the production of clean fuel in as little as a decade. Scientists Carole Lartigue and colleagues from the J. Craig Venter Institute in Rockville, Maryland, have published their results in a recent issue of Science. In addition to being a proof-of-concept experiment, the researchers hope that genome transplantation will enable the production of synthetic microbes for green energy sources, pharmaceuticals, chemicals and textiles. The scientists’ results show that it is possible to transplant the complete set of DNA—the genome—from one species into the genome of a different species, so that the recipient organism is phenotypically and genotypically identical to the donor organism. In their experiment, the researchers used two species of bacteria that belong to a group of organisms called mycoplasmas due to their small genomes (making them easier to handle) and lack of a cell wall (enabling easier insertion of DNA).

In the experiment, Mycoplasma mycoides Large Colony (LC) served as the donor, and Mycoplasma capricolum the receiver. Both bacteria are mild pathogens of goats, and are genetically similar, sharing about 75% of their genomic material. The researchers explained that the transplantation method is simple in concept, though complicated to execute. First, the proteins were stripped from the M. mycoides LC cells, resulting in “naked” DNA that can be passed between cells. Then this intact DNA was incubated briefly with M. capricolum cells, soaking in a solution that caused the M. capricolum cells to fuse together. As two of these recipient cells fused, they sometimes encapsulated a donor DNA chromosome.