Life in miniature: scientists whittle away genes from bacteria to create smallest viable genome

American scientists have created the smallest ever viable genome in a living organism, with just enough essential genes to function and reproduce on its own, in a major step toward unlocking the mysteries of how life is created.

After systematically removing genes from naturally occurring bacteria, the researchers ended up with the synthetic genome of the bacteria dubbed JCVI-syn3.0, which only carries 473 genes, compared to about 20,000 for a human being.

But lead researchers Craig Venter - the first to sequence the human genome - and Clyde Hutchinson and their colleagues have not yet determined the functions of 149 of the genes, about a third of the total.

“Investigators’ first task is to probe the roles of those genes, which promise new insights into the basic biology of life,” said Chris Voigt, a synthetic biologist at Massachusetts Institute of Technology who did not participate in the research.

But several potentially homologous genes have been found in other organisms, suggesting they encode universal proteins with functions that for now remain undetermined.

Researchers identified quasi-essential genes, which are required for robust growth but not for life. The study was published in Thursday’s edition of the journal Science.

Through a series of experiments, they obtained a synthetic, reduced genome that was as small as possible because no more genes could be disrupted.