Overview

• Scientists recoded the entire 4-megabase E. coli genome with over 100,000 synonymous edits to operate using only 57 of the natural 64 codons.
• The redesigned genome was built from 38 synthetic DNA fragments of roughly 100 kilobases each, with fitness screening after each assembly step.
• Syn57 grows about four times slower than its natural counterpart and displays a distinct global gene expression profile indicating broad physiological adaptation.
• Next steps include improving the slow growth phenotype and removing transfer RNAs for the freed codons to assess the strain’s functional utility.
• Freed codons create opportunities for creating virus-resistant microbes and incorporating non-natural amino acids in industrial biomanufacturing applications.