By Neil Bowdler
BBC science reporter
Scientists in the US say they have taken a major step towards producing life from scratch in the laboratory.
Dr Venter says the research brings him closer to creating synthetic life
Dr Craig Venter says in the journal Science that his team successfully transplanted an entire genome from one bacterium cell to another.
He says he hopes eventually to use the technique to create designer microbes, which could produce artificial fuel or help clean up toxic waste.
Dr Venter was a pioneer in mapping the human genome.
The ultimate plan is to stitch together artificial chromosomes, proteins and other building blocks with the aim of jumpstarting their designer microbe to life. But Dr Venter concedes that this may be a long way away, but he says he has taken an important key step towards that goal.
His team, essentially, snatched the body of another life-form and invaded it with a new genetic code.
This, he says, will be a key tool in testing the artificial chromosomes - or DNA bundles - he plans to make.
"What's in this paper is the result of taking a native chromosome from one species," Dr Venter explained.
"That chromosome was transplanted, inserted through the cell walls, the cell membrane of a second species and, after several days of growth and cell division, the original chromosome in the cell disappears and we have cells containing only the transplanted chromosome."
But there are those who are worried about what Dr Venter is doing.
Some fear the technology could be used to create biological weapons or simply that something unforeseen may emerge from the laboratory.
Others are concerned that his institute's efforts to patent research could restrict scientific advances elsewhere.
But Dr Venter says he is doing nothing that other institutes do not already do.
"Over the last several years we have had to develop novel techniques and approaches that have not existed before because this field has not existed before," he said.
"The Venter Institute and the Synthetic Genomics Company are doing what most major institutions do - that is we file patents on these unique techniques."