Our method for experimental testing of a phage host-range without the need for culturing the host has been just published in Nature Microbiology. It involves fluorescent staining of anonymous phages collected from an environment which are combined with anonymous environmental bacteria, and the subset of bacteria tagged by fluorescent viruses is collected by fluorescence activated cells sorting and analysed on single-cell level. This "viral tagging" method has been demonstrated on human gut microbiome to explore possible interactions between phages and their hosts coming from different human volunteers which can have implications for faecal microbiota transplant therapy. The resulting host-phage network revealed hosts for hundreds of previously unknown viruses and it showed that the phages are mostly species-specific (and not strain-specific as previously though), and only a smaller number of phages have a wider host-range. In addition, we found out that the phages in the human gut have possibly low burst sizes and that the prophage induction in the gut is common, thus the phages do not perturb the human gut microbiome composition heavily on a daily basis.