One small bacterial genome, to go.

Before attempting to create a new life-form in the laboratory, one group of scientists is pausing to allow reflection on the consequences of such an effort. Their experiment concerns the intriguing issue of how few genes a free-living organism needs (SN: 9/28/96, p. 198).

The bacterium with the smallest known genome, Mycoplasma genitalium, has just under 500 genes. Scientists at The Institute for Genomic Research (TIGR) in Rockville, Md., have been deactivating those genes one by one to determine which are required for life. The final tally stands at around 300 essential genes, says J. Craig Venter, former president of TIGR.

To test whether these 300 or so genes alone can sustain life, Venter and his colleagues have contemplated making an artificial bacterial chromosome containing only those genes. The biologists would then slip this chromosome into an empty bacterial membrane and see whether their creation springs into action. The researchers have temporarily halted their work to give a group of bioethicists and religious scholars time to develop a report on the implications of the provocative experiment.

There's no delay, however, in Venter's controversial plan to quickly sequence all the genes in the human body (SN: 5/23/98, p. 334). His new company, Celera Genomics in Rockville, Md., could have the complete human genome next summer, he says.