Unlike the human gut, few large-scale cultivation efforts have been directed at freshwater bacterioplankton, resulting in many abundant clades remaining uncultivated or poorly represented. The isolation of new microorganisms provides an invaluable resource for experimental validation of phenotype, ecology, and evolutionary processes. While the number of cultivars in culture collection is growing, the majority of isolates come from a limited number of phylogenetic groups and environments, necessitating investment in new cultivation efforts and limiting studies aimed at resolving microdiversity within subpopulations and biogeographic distribution.