A new kind of machine for decoding DNA may help bring costs so low that it would be feasible to decode an individual’s DNA for medical reasons. The machine, developed by 454 Life Sciences of Branford, Conn., was used to resequence the genome of a small bacterium in four hours, compared to four to six months in 1995.

The machine uses luciferase, the chemical in fireflies, to generate a flash of light each time a unit of DNA is correctly analyzed, using more than a million DNA-containing wells.