In a single decade, CRISPR has made a dramatic impact on literally every facet of biotechnology. This game-changing system is traditionally programmed to make cuts at very specific parts of the genome, altering the code to cure disease. But a new class of CRISPRs discovered by Leo’s colleagues don’t simply cut DNA -- they integrate entirely new genetic material at targeted locations. With it, Leo generates a new method to perform very specific and highly efficient genome engineering on bacteria and describes the multitude of ways it can generate strains that revolutize commodity molecule synthesis and medicine.