No abstract

Microorganisms play a crucial role in mediating global biogeochemical cycles in the marine environment. By reconstructing the genomes of environmental organisms through metagenomics, researchers are able to study the metabolic potential of Bacteria and Archaea that are resistant to isolation in the laboratory. Utilizing the large metagenomic dataset generated from 234 samples collected during the Tara Oceans circumnavigation expedition, we were able to assemble 102 billion paired-end reads into 562 million contigs, which in turn were co-assembled and consolidated in to 7.2 million contigs ≥2 kb in length. Approximately 1 million of these contigs were binned to reconstruct draft genomes. In total, 2,631 draft genomes with an estimated completion of ≥50% were generated (1,491 draft genomes >70% complete; 603 genomes >90% complete). A majority of the draft genomes were manually assigned phylogeny based on sets of concatenated phylogenetic marker genes and/or 16S rRNA gene sequences. The draft genomes are now publically available for the research community at-large.

Microorganisms play a crucial role in mediating global biogeochemical cycles in the marine 14 environment. By reconstructing the genomes of environmental organisms through 15 metagenomics, researchers are able to study the metabolic potential of Bacteria and Archaea that 16 are resistant to isolation in the laboratory. Utilizing the large metagenomic dataset generated 17 from 234 samples collected during the Tara Oceans circumnavigation expedition, we were able 18 to assemble 102 billion paired-end reads into 562 million contigs, which in turn were co-19 assembled and consolidated in to 7.2 million contigs ≥2kb in length. Approximately 1 million of 20 these contigs were binned to reconstruct draft genomes. In total, 2,631 draft genomes with an 21 estimated completion of ≥50% were generated (1,491 draft genomes >70% complete; 603 high-22 quality genomes >90% complete). A majority of the draft genomes were manually assigned 23 phylogeny based on sets of concatenated phylogenetic marker genes and/or 16S rRNA gene 24 sequences. The draft genomes are now publically available for the research community at-large. 25 26

Aerobic anoxygenic phototrophs (AAnPs) are common in marine environments and are associated with photoheterotrophic activity. To date, AAnPs that possess the potential for carbon fixation have not been identified in the surface ocean. Using the Tara Oceans metagenomic dataset, we have identified draft genomes of nine bacteria that possess the genomic potential for anoxygenic phototrophy, carbon fixation via the Calvin-Benson-Bassham cycle, and the oxidation of sulfite and thiosulfate. Forming a monophyletic clade within the Alphaproteobacteria and lacking cultured representatives, the organisms compose minor constituents of local microbial communities (0.1–1.0%), but are globally distributed, present in multiple samples from the North Pacific, Mediterranean Sea, the East Africa Coastal Province, and the Atlantic. This discovery may require re-examination of the microbial communities in the oceans to understand and constrain the role this group of organisms may play in the global carbon cycle.