Starting from custom-made segments of DNA, scientists have succeeded in putting together an entire microbial genome in the lab. The researchers plan to transplant this genome into a microbe in the hope that the cell will "boot up" and use the synthetic DNA.
The completed genome is a single DNA molecule with about 583,000 letters of genetic code—18 times the size of the previous record for laboratory—made DNA.
Researchers at the J. Craig Venter Institute in Rockville, Md., based their homemade genome on that of Mycoplasma genitalium, a single-celled parasite that infects people's genitals. The parasite has one of the smallest known genomes.
To distinguish the synthetic genome from a natural one, team leader Hamilton O. Smith and his colleagues added telltale "bar codes" of genetic code to their recipe. The researchers also crippled the gene that makes the parasite infectious.