An American biologist has stepped into the shoes of Baron Frankenstein by breathing life into a bacterium using genes assembled in the laboratory.

The creation of the "synthetic cell", described as a "landmark" by one British expert, is a 15-year dream come true for maverick genetics entrepreneur Dr Craig Venter.

It has major implications for genomics, including the manufacture of artificial organisms designed for specific tasks such as making vaccines or cleaning up pollution.

But experts recognise that as Mary Shelley demonstrated in her famous novel, there are potential dangers too. Synthetic life could, for instance, pave the way to terrifying biological weapons.

Dr Venter's researchers explain in the journal Science how they effectively "re-booted" a simple microbe by transplanting into it a set of genetic code sequences that were built from scratch.

British expert Professor Paul Freemont, co-director of the EPSEC Centre for Synthetic Biology at Imperial College London, said: "The paper... is a landmark study that represents a major advance in synthetic biology.

"The applications of this enabling technology are enormous and one might argue this is a key step in the industrialisation of synthetic biology leading to a new era of biotechnology."