Researchers have used CRISPR-Cas9 to develop a technology that can target any gene in the yeast Saccharomyces cerevisiae and turn it off by deleting single letters from its DNA sequence. Such genome-scale engineering — in contrast to traditional strategies that only target a single gene or a limited number of genes – could be useful for industry, where S. cerevisiae is widely used to produce ethanol, industrial chemicals, lubricants, pharmaceuticals and more.