Colorized scanning electron microscope image of E. coli NIAID Two years ago, scientists in Britain swapped out the DNA of the bacteria Escerichia coli for a genetic coding program that was entirely human-made. At the time, it was the largest and most complex synthetic genome ever created. On Thursday, that same group of researchers at the Medical Research Council Laboratory of Molecular Biology reported in Science that with continued tinkering, they’ve made their artificial life form virtually invincible to viral infection. Other adjustments to the bacteria’s designer genome endowed the bug with the ability to string together non-natural amino acids to produce proteins never before seen inside a living cell.