Scientists have successfully added multiple “unnatural” amino acids to a strain of bacteria, a breakthrough on the path to genetically engineered microbes that create useful things for people such as life-saving medicines and biofuels.

“We are adding components to the bug so that the bug can do something that a natural bug usually can’t do,” Lei Wang at the Salk Institute for Biological Studies told me today. “We are trying to make it do new tricks.”