Abstract Diversity-generating retroelements (DGRs) are genetic elements that use error-prone reverse transcription to hypermutate specific target genes, most often the receptor-binding proteins of phages. They are enriched in human gut viruses, where they are hypothesised to enable phages expand their host range. Yet DGR-mediated host-range expansion across bacterial species has so far only been predicted in silico and has not been examined directly within complex microbial communities.
