The OceanDNA MAG catalog contains over 50,000 prokaryotic genomes originated from various marine environments

Marine microorganisms are immensely diverse and play fundamental roles in global geochemical cycling. Recent metagenome-assembled genome studies, with special attention to large-scale projects such as Tara Oceans, have expanded the genomic repertoire of marine microorganisms. However, published marine metagenome data has not been fully explored yet. Here, we collected 2,057 marine metagenomes (>29 Tera bps of sequences) covering various marine environments and developed a new genome reconstruction pipeline. We reconstructed 52,325 qualified genomes composed of 8,466 prokaryotic species-level clusters spanning 59 phyla, including genomes from deep-sea deeper than 1,000 m (n=3,337), low-oxygen zones of <90 mol O2 per kg water (n=7,884), and polar regions (n=7,752). Novelty evaluation using a genome taxonomy database shows that 6,256 species (73.9%) are novel and include genomes of high taxonomic novelty such as new class candidates. These genomes collectively expanded the known phylogenetic diversity of marine prokaryotes by 34.2% and the species representatives cover 26.5 - 42.0% of prokaryote-enriched metagenomes. This genome resource, thoroughly leveraging accumulated metagenomic data, illuminates uncharacterized marine microbial dark matter lineages.