Natural competence promotes high rates of DNA transfer between strains of the core bee gut bacterium Snodgrassella alvi

Sexual recombination and horizontal gene transfer are expected to improve the survival of host-associated bacteria that face colonization bottlenecks and intense competition. We serendipitously observed recombination between Snodgrassella alvi strains within bees, which led us to discover that this core member of the bee gut microbiota is naturally competent, including under laboratory conditions. High rates of gene transfer via DNA release and uptake by S. alvi have implications for how it has evolved in managed hives and suggest opportunities for using in situ microbiome engineering to protect bee health.