Retron Library Recombineering (RLR) is a modern gene editing technique that can produce millions of mutations at once and ‘barcodes’ mutant bacterial cells so that the whole pool can be screened at the same time. It can be used in situations where CRISPR is toxic or impossible to use, and it improves editing rates.
Although the CRISPR-Cas9 gene editing technology has become the poster child for synthetic biology advancement, it is not without flaws. CRISPR-Cas9 can also be programmed to locate and cut specific pieces of DNA, but altering the DNA to produce desired mutations necessitates convincing the cell to repair the break with a new piece of DNA. This bait-and-switch can be difficult to pull off, and it can even backfire.