In a pioneer study published in Cell Host & Microbe, Researchers at Osaka City University and The Institute for Medical Science, The University of Tokyo, reported intestinal bacterial and viral metagenome information from the fecal samples of 101 healthy Japanese individuals. This analysis, leveraging host bacteria-phage associations, detected phage-derived antibacterial enzymes that control pathobionts. As proof of concept, phage-derived endolysins are shown to regulate C. difficile infection in mice.