Scientists may soon have the ability to create completely new living organisms from the raw chemical building blocks of life.

This was the prediction of a leading geneticist speaking at the annual meeting of the American Association for the Advancement (AAAS), taking place in Anaheim in southern California.

Dr Craig Venter of the Celera Genomics Corporation said the creation of man-made microbes from a cocktail of molecules could reveal how life first evolved on Earth, but acknowledged such an experiment raised a multitude of ethical issues.

Bare essentials

The idea of creating a lifeform from a soup of chemicals may sound like science fiction. But advances in genetics are taking researchers ever closer to that possibility, according to Dr Venter.

He is working on a microorganism called Mycoplasma genitalium. It has the smallest number of genes in its single cell of any living thing - a mere 470 compared to our 80,000 to 1000,000 genes.

By selectively removing each gene, Dr Venter is trying to discover the smallest number necessary to provide the simplest genetic blueprint for a self-supporting microorganism.

New genes

So far, his team have got M. genitalium down to about 300 essential genes. Even so, they are not entirely sure what they all do. "Fifty percent of the genes in every genome are new to science and we don't know what they do," Dr Venter said.

The same is true even of M. genitalium's 300 basic genes. "One hundred of these we, as scientists, have no clue as to what they do. It's very humbling."

Nevertheless, Dr Venter reckons the data being gathered could form the basis for trying to put together an artificial M. genitalium.

Playing God

The genetic blueprint of all organisms is coded in the molecule DNA. And as researchers can construct a DNA molecule to any specification, it should be possible - in theory - to design a genetic blueprint for a simple man-made microbe.

Add this DNA to a test-tube of substances such as amino acids, fats and sugars, and the DNA should build a living thing around itself. Many people may condemn this project as the ultimate step in scientists playing God, though Dr Venter believes it could help solve the mystery of how life first evolved on Earth.

At the meeting though, he warned that the technique could be abused to create new and deadly microbes for use in biological weapons. He suggested for this reason alone, the final step of creating life in the laboratory may be banned - at least in the United States.