title: Co-occurrence Analysis of Microbial Taxa in the Atlantic Ocean Reveals High Connectivity in the Free-Living Bacterioplankton.
abstract: We determined the taxonomic composition of the bacterioplankton of the epipelagic zone of the Atlantic Ocean along a latitudinal transect (51°S-47°N) using Illumina sequencing of the V5-V6 region of the 16S rRNA gene and inferred co-occurrence networks. Bacterioplankon community composition was distinct for Longhurstian provinces and water depth. Free-living microbial communities (between 0.22 and 3 μm) were dominated by highly abundant and ubiquitous taxa with streamlined genomes (e.g., SAR11, SAR86, OM1, Prochlorococcus) and could clearly be separated from particle-associated communities which were dominated by Bacteroidetes, Planktomycetes, Verrucomicrobia, and Roseobacters. From a total of 369 different communities we then inferred co-occurrence networks for each size fraction and depth layer of the plankton between bacteria and between bacteria and phototrophic micro-eukaryotes. The inferred networks showed a reduction of edges in the deepest layer of the photic zone. Networks comprised of free-living bacteria had a larger amount of connections per OTU when compared to the particle associated communities throughout the water column. Negative correlations accounted for roughly one third of the total edges in the free-living communities at all depths, while they decreased with depth in the particle associated communities where they amounted for roughly 10% of the total in the last part of the epipelagic zone. Co-occurrence networks of bacteria with phototrophic micro-eukaryotes were not taxon-specific, and dominated by mutual exclusion (~60%). The data show a high degree of specialization to micro-environments in the water column and highlight the importance of interdependencies particularly between free-living bacteria in the upper layers of the epipelagic zone.
authors.affiliation: Group Microbial Communication, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Milici
authors.affiliation: Group Microbial Communication, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Zhi-Luo
authors.initials: ZL
authors.lastname: Deng
authors.affiliation: Group Microbial Communication, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Tomasch
authors.affiliation: UMR 7144 - Sorbonne Universités, UPMC Univ Paris 06Roscoff, France; Centre National de la Recherche Scientifique, UMR 7144Roscoff, France.
authors.forename: Johan
authors.initials: J
authors.lastname: Decelle
authors.affiliation: Group Microbial Interactions and Processes, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Wos-Oxley
authors.affiliation: Group Microbial Communication, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Group Microbial Interactions and Processes, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Ruy
authors.initials: R
authors.lastname: Jáuregui
authors.affiliation: Group Microbial Interactions and Processes, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Iris
authors.initials: I
authors.lastname: Plumeier
authors.affiliation: Biology of Geological Processes, Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg Oldenburg, Germany.
authors.forename: Helge-Ansgar
authors.initials: HA
authors.lastname: Giebel
authors.affiliation: Biology of Geological Processes, Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg Oldenburg, Germany.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Badewien
authors.affiliation: Biology of Geological Processes, Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg Oldenburg, Germany.
authors.forename: Mascha
authors.initials: M
authors.lastname: Wurst
authors.affiliation: Group Microbial Interactions and Processes, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Dietmar H
authors.initials: DH
authors.lastname: Pieper
authors.affiliation: Biology of Geological Processes, Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg Oldenburg, Germany.
authors.forename: Meinhard
authors.initials: M
authors.lastname: Simon
authors.affiliation: Group Microbial Communication, Helmholtz-Center for Infection Research Braunschweig, Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Wagner-Döbler
keywords: 16S rRNA analysis; Atlantic Ocean; bacteria-bacteria interactions; bacterioplankton; co-occurrence; network analysis; next generation sequencing; phytoplankton-bacteria interactions