Dr Basem Al-Shayeb, a member of saf, publishes a study in the journal Cell titled (Diverse virus-encoded CRISPR-Cas systems include streamlined genome editors). CRISPR-Cas systems are host-encoded pathways that protect microbes from viral infection using an adaptive RNA-guided mechanism. Using genome-resolved metagenomics, Al-Shayeb and coworkers find that CRISPR systems are also encoded in diverse bacteriophages, where they occur as divergent and hypercompact anti-viral systems. These findings reveal a new source of CRISPR-Cas enzymes in phages and highlight their value as genome editors in plant and human cells.