World’s first stable semi-synthetic organism created

In a breakthrough, scientists have created the first stable semi-synthetic organism — a single-celled bacterium — that may play important roles in drug discovery and other applications. Life’s genetic code has only ever contained four natural bases. These bases pair up to form two base pairs — the rungs of the DNA ladder — and they have simply been rearranged to create all life as we know it, from bacteria to humans. Building on earlier research in which they synthesised a DNA base pair, scientists at The Scripps Research Institute (TSRI) in the US created a new bacterium that uses the four natural bases (called A, T, C and G), which every living organism possesses, but that also holds as a pair two synthetic bases called X and Y in its genetic code.

Researchers have now shown that the single-celled organism can hold on to the synthetic base pair as it divides. “We’ve made this semi-synthetic organism more life-like,” said Floyd Romesberg, professor at TSRI. Researchers said the work could be used to create new functions for single-celled organisms that play important roles in drug discovery and much more. They had earlier showed that E. coli bacteria could hold a synthetic base pair in their genetic code. However, they could not keep the base pair in their code indefinitely as they divided.