BarbaraHudson (3785311) writes In Jurassic Park, scientists tweak dinosaur DNA so that the dinosaurs were lysine-deficient in order to keep them from spreading in the wild. Scientists have taken this one step further as a way to keep genetically modified E. coli from surviving outside the lab. In modifying the bacteria's DNA to thwart escape, two teams altered the genetic code to require amino acids not found in nature. One team modified the genes that coded for proteins crucial to cell functions so that that produced proteins required the presence of the synthetic amino acid in the protein itself. The other team focused on 22 genes deemed essential to a bacterial cell's functions and tied the genes' expression to the presence of synthetic amino acids. For the bacteria to survive, these synthetic amino acids had to be present in the medium on which the bacteria fed. In both cases, the number of escapees was so small as to be undetectable."