How artificial life was made

Pioneering US geneticist Dr Craig Venter and his team at the J Craig Venter Institute in Maryland have built an artificial version of a bacterium’s DNA and incorporated it into a cell from which the original DNA had been removed.

The newly created bacteria, named Synthia, reproduced using the artificial version of the DNA. Strictly speaking, it is only the DNA in the cell that is entirely synthetic, but these cells are the first life-form to be completely controlled by synthetic DNA. Dr Venter says the achievement heralds the dawn of a new era in which life is made to benefit humanity, such as bacteria that soak up carbon dioxide from the atmosphere or manufacture vaccines.

1. Dr Venter’s team decoded the DNA of an existing bacterium (Mycoplasma mycoides), which causes mastitis in goats. They used a computer to read each of the ‘letters’ of genetic code: plotting the sequence of amino acids that carry the cell’s instructions.

2. They copied the code, made up of more than a million letters, and chemically constructed a synthetic version. They also added certain genetic signatures or ‘watermarks’ to identify it as a built-in-the-lab version.

3. The chromosome was inserted into another species of bacterium from which the original DNA had been removed. That cell began making new proteins, following the instructions of its synthetic DNA. It also replicated, creating more than a billion copies, again controlled by the synthetic DNA. The ability to reproduce is regarded as the basic definition of life.