Single-cell-resolved genome atlas of prokaryoplankton inhabiting the ocean's interior.

The ocean's aphotic interior harbors three-quarters of planktonic bacteria and archaea (prokaryoplankton), whose composition, ecology, and biotechnological potential remain poorly constrained. To address this knowledge gap, we created Global Oceans Reference Genomes (GORG)-Dark, a dataset of 9,698 genomes from individual prokaryoplankton cells sampled unselectively across a broad range of depths, geographic locations, and environmental conditions below the ocean's photic surface. Biogeographic analyses revealed prokaryoplankton vertical stratification extending to abyssal depths, the presence of particle-attached lineages of Pelagibacterales, and the previously overlooked abundance of Patescibacteria and Nanoarchaeota in the Baltic and Black Seas. We identified coding potential for chemolithoautotrophy, pharmacologically relevant secondary metabolisms, and a distinct type of proteorhodopsins in prokaryoplankton lineages prevalent throughout the aphotic ocean. This study offers a quantitative, global assessment of the composition and coding potential of microorganisms inhabiting the vast ocean's interior and contributes an extensive, single-cell-resolved dataset to microbial oceanography's cyberinfrastructure.