Scientists from Maryland's Institute for Genomic Research took a genetic approach to the question "what is life?" By studying Mycoplasma genitalium, one of the world's simplest one-celled organisms, they concluded that 265 to 350 genes are needed for life, concludes a report in Friday's journal Science.
One way to prove that would be to try creating a microscopic organism from scratch, such as "designer bacteria" to break down environmental toxins. The report raises questions about whether scientists ever should attempt such a feat.
The work was halted in 1998 because of ethics concerns, said J. Craig Venter, the institute's founder, who wants more public discussion of such a project before it proceeds.
But an accompanying report in Science by a group of ethicists concluded that as long as the scientific and ethical implications are carefully weighed first, there is no major reason not to create a living organism.
"The ability to create a new organism with a minimal genome is still a long way off," the ethicists stressed, noting that much additional work is necessary to ensure scientists truly know this one bacterium's bare minimum genes.
And there would be serious questions that require much caution. After all, the same technology that might create environmental-helper bacteria could also "harm our health or the environment," the ethicists warned.
Still, such research "may provide insight into the origins of life, bacterial evolution or the control of bacterial metabolism," they wrote. The public must decide "how can the technology be used for the benefit of all."
Humans have an estimated 80,000 to 100,000 genes. In contrast, the geneticists studied a bacterium with just 517 genes - they simply inactivated two genes at a time to see which appeared vital to its life.