WASHINGTON (AFP) - US scientists have taken a major step toward creating the first ever artificial life form by synthetically reproducing the DNA of a bacteria, according to a study published Thursday. The move, which comes after five years of research, is seen as the penultimate stage in the endeavour to create an artificial life form based entirely on a man-made DNA genome -- something which has tantalised scientists and sci-fi writers for years. "Through dedicated teamwork we have shown that building large genomes is now feasible and scalable so that important applications such as biofuels can be developed," said Hamilton Smith, from the J. Craig Venter Institute, in the study published in Science. The research has been carried out at the laboratories of the controversial celebrity US scientist Craig Venter, who has hailed artificial life forms as a potential remedy to illness and global warming. However, the prospect of engineering artificial life forms is highly controversial and is likely to arouse heated debate over the ethics and potential ramifications of such an advance. It is one of the Holy Grails of science, but also one that stirs deep fears as forseen in Aldous Huxley's 1932 novel "Brave New World" in which natural human reproduction is eschewed in favor of babies grown artificially in laboratories. Venter said in a statement: "This extraordinary accomplishment is a technological marvel that was only made possible because of the unique and accomplished ... team." His researchers had "dedicated the last several years to designing and perfecting new methods and techniques that we believe will become widely used to advance the field of synthetic genomics," he added. Lead author Dan Gibson said the team had completed the second step in a three-step process to create a synthetic organism. In the final stage of their research which they are already working on, the Maryland-based team will attempt to create a bacteria based purely on the synthetic genome sequence of the Mycoplasma genitalium bacteria. The bacteria, which causes certain sexually transmitted diseases, has one of the least complex DNA structures of any life form, composed of just 580 genes. In contrast, the human genome has some 30,000. The chromosome which Venter and his team has created is known as Mycoplasma laboratorium and, in the final step of the process, will be transplanted into a living cell where it should "take control," effectively becoming a new life form. The new bacteria will therefore be largely artificial, though not entirely, because it is composed of building blocks from already existing organisms. "When we started this work several years ago, we knew it was going to be difficult because we were treading into unknown territory," said Smith. But other scientists remain cautious, saying Venter and his team are still a long way from being able to create artificial life. They point to a tell-tale footnote in the study which details a problem in slotting in one of the cloned genes. Eckard Wimmer, professor of molecular biology at New York University, said it was clear from Venter's study that the team had not yet created artificial life. He said he was left with "the unpleasant feeling whether or not the synthetic DNA was indeed proper and able for biological function." His fears were echoed by Helen Wallace, a biologist and spokesperson for GeneWatch UK, who said that while Venter's team has managed a technical feat, it is some way from being artificial life. "Venter is not God ... He's a long way from creating life," she told AFP. "It's a type of genetic engineering which would allow people to make much bigger genetic changes, which means that in the future you could create organisms with new gene sequences."