There is a gap in knowledge on broad-scale diversity and functional patterns along the continuum between the photic and the dark ocean microbes, including trends in genome size (GS) and functional diversity. To address this gap, we present the Malaspina Microbial Vertical Profiles Metagenomes dataset, comprising 76 microbial metagenomes (0.2-3um) collected in 11 stations in the tropical and subtropical open oceans from 3 to 4,000 m deep, a 46.3 million gene catalog and 1,228 Metagenome-Assembled Genomes (MAGs). Our results show increased functional richness in the bathypelagic and a strong positive association between GS and depth for the most abundant phyla in samples up to 1,000 m, while this association is absent in the bathypelagic. Conversely, lower abundance taxa displayed a bimodal distribution of GS, with a smaller peak in the mesopelagic and a larger peak in the bathypelagic. Opposing trends were observed for protein-encoding gene density and functional diversity across epipelagic and deep ocean MAGs. Specifically, protein-encoding gene density was higher at the epipelagic and decreased towards the bathypelagic for most of the taxa, pointing out that genome streamlining generally holds true, but it is not universal for all microbes. Larger prokaryotic GS in the bathypelagic was associated with a higher prevalence of prophages and defense systems. We suggest that a combination of factors, including genome streamlining, metabolic diversification, viral infection, and molecular defense systems, drive the genomic diversity of marine prokaryotes across ocean layers.

Primary Presenter: Pablo Sánchez, Institut de Ciències del Mar, CMIMA-CSIC (pablosanchez@icm.csic.es)

Authors:

Pablo Sánchez, Institut de Ciències del Mar, CSIC  (pablosanchez@icm.csic.es)

Felipe Coutinho, Institut de Ciències del Mar, CSIC  (fhernandes@icm.csic.es)

Marta Sebastián, Institut de Ciències del Mar, CSIC  ()

Massimo Pernice, Institut de Ciències del Mar, CSIC  ()

Raquel Rodríguez-Martínez, Universidad de Antofagasta  ()

Guillem Salazar, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich  ()

Francisco Cornejo-Castillo, Institut de Ciències del Mar, CSIC  ()

Stéphane Pesant, European Molecular Biology Laboratory  ()

Susana Agustí, King Abdullah University of Science and Technology (KAUST)  ()

Takashi Gojobori, King Abdullah University of Science and Technology (KAUST)  ()

Ramiro Logares, Institut de Ciències del Mar, CSIC  ()

María Montserrat Sala, Institut de Ciències del Mar, CSIC  ()

Dolors Vaqué, Institut de Ciències del Mar, CSIC  ()

Ramon Massana, Institut de Ciències del Mar, CSIC  ()

Carlos Duarte, King Abdullah University of Science and Technology (KAUST)  ()

Silvia Acinas, Institut de Ciències del Mar, CSIC  ()

Josep Gasol, Institut de Ciències del Mar, CSIC  ()