show Abstracthide AbstractPlanarian worms have been used for decades as models for development and regeneration. These worms live in aquatic environments with constant exposure to microbes, but the diversity of planarian microbiomes and the mechanisms by which bacteria may mediate regeneration outcomes are largely unknown. We characterized the taxonomic and functional diversity of the Dugesia japonica microbiome using culture-based approaches, amplicon metagenomics, and metatranscriptomics. We also determined how individual members of the D. japonica microbiome impact regeneration outcomes.