Synthetic life forms on horizon?

Taking a significant step toward the creation of synthetic forms of life, researchers reported Thursday that they had manufactured the entire genome of a bacterium by stitching together its chemical components.

Scientists previously constructed the complete DNA of viruses, but this is the first time it has been done for bacteria, which are far more complex.

The feat is a watershed for the emerging field called synthetic biology, which involves the design of organisms to perform particular tasks, such as making biofuels. Synthetic biologists envision being able to design an organism on a computer, press the "print" button to have the necessary DNA made and put that DNA into a cell to produce a custom-made creature.

"What we are doing with the synthetic chromosome is going to be the design process of the future," said J. Craig Venter, the boundary-pushing gene scientist.

Venter assembled the team that made the bacterial genome as part of his well-publicized quest to create the first synthetic organism. The work was published online Thursday by the journal Science.

There are concerns synthetic biology could be used to make pathogens, or that errors by well-intended scientists could produce organisms that run amok. The genome of the smallpox virus can in theory be synthesized using the techniques reported Thursday since it is only about one-third the size of the genome manufactured by Venter's group.

But there are many hurdles to overcome before Venter's vision of "life by design" is realized. The synthetic genome made by Venter's team was not designed from scratch but rather was a copy, with only a few changes, of the genetic sequence of a natural bacterium called Mycoplasma genitalium.

Moreover, Venter's team, led by Nobel laureate Hamilton Smith, has yet to accomplish the next — and biggest — step. That would be to insert the synthetic chromosome into a living microbe and have it "boot up" and take control of the organism's functions.

If that happened, it would be considered by some to be the creation of the first synthetic organism. The failure to achieve that tempered the reaction of some outside scientists.

"Right now, all they've done is shown they can buy a bunch of DNA and put it together," said George Church, a professor of genetics at Harvard Medical School.

But David Magnus, director of Stanford University's Center for Biomedical Ethics, said, "What it might mean for the future is incredible. We just need to make sure we stay on top of the pitfalls."

Material from the San Jose Mercury News is included in this report.