Controversial biologist Craig Venter, who led the private effort to map the human genome, says that he has moved one step further in his endeavour to create the first artificial life form, as he has replaced the entire genetic code of one microbe with that of another.
In the breakthrough experiment, the researcher substituted the DNA of a bacterium with that of a close relative to turn it into a different species.
The success of his work paves the way for future studies aimed at creating synthetic life by doing the same experimentation on a genome that has been man-made from scratch.
Dr Venter, who recently applied for a patent on a DNA sequence described as the 'minimal genome', has been researching ways to make artificial organisms for long, so that new species of bacteria that produce environmentally friendly fuels such as hydrogen could be produced.
With the success of his groundbreaking genome-swapping technique, he has reached much closer to the accomplishment of his goal.
He says that the technique can be used to insert a DNA sequence that he has built into the shell of an existing bacterium. While the cell's membrane would be natural, its the genetic code that contains the instructions for life would be wholly artificial.
"It's like changing a Macintosh computer into a PC by inserting a new piece of software," the Times Online quoted Dr Venter as saying.
The technique may allow scientists to create and insert artificial chromosomes carrying added genes into the genome, although further studies would be required to achieve this objective.
During the experiment, published in the journal Science, the researchers from the J. Craig Venter Institute in Rockville in Maryland first extracted DNA from the donor bacterium species, Mycoplasma mycoides. Thereafter, they inserted it into the host bacterium, a close relative known as Mycoplasma capricolum.
The researchers noted that after the DNA transplant, bacterial cells were using only the added genome, and had become biologically identical to the donor bacteria. The host cells' genomes had been silenced or destroyed.
"We don't know for certain how the donor genome takes over. But what is clear is that the technique works," Dr Venter said.
The project has drawn criticism from groups concerned that it is unethical to patent new forms of life, and that similar techniques could be used to create dangerous new germs.
Dr Venter, however, insisted that his team had worked under ethical scrutiny at every stage, and even interrupted the project for 18 months while a bioethics panel was convened to review it.
"I don't think there has ever been another field of science that has had so much public input and analysis before there have been any results. Potential abuses such as biological warfare concern everyone in the field," he said.