title: Impacts of chemical gradients on microbial community structure.
abstract: Succession of redox processes is sometimes assumed to define a basic microbial community structure for ecosystems with oxygen gradients. In this paradigm, aerobic respiration, denitrification, fermentation and sulfate reduction proceed in a thermodynamically determined order, known as the 'redox tower'. Here, we investigated whether redox sorting of microbial processes explains microbial community structure at low-oxygen concentrations. We subjected a diverse microbial community sampled from a coastal marine sediment to 100 days of tidal cycling in a laboratory chemostat. Oxygen gradients (both in space and time) led to the assembly of a microbial community dominated by populations that each performed aerobic and anaerobic metabolism in parallel. This was shown by metagenomics, transcriptomics, proteomics and stable isotope incubations. Effective oxygen consumption combined with the formation of microaggregates sustained the activity of oxygen-sensitive anaerobic enzymes, leading to braiding of unsorted redox processes, within and between populations. Analyses of available metagenomic data sets indicated that the same ecological strategies might also be successful in some natural ecosystems.
authors.affiliation: Department of Geoscience, University of Calgary, Calgary, AB, Canada.|Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Chen
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Hanke
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.|Institute for Genome Research and Systems Biology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany.
authors.forename: Halina E
authors.initials: HE
authors.lastname: Tegetmeyer
authors.affiliation: Institute for Genome Research and Systems Biology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Kattelmann
authors.affiliation: Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.|UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA.|Department of Molecular Oncology, The Moffitt Cancer Center and Research Institute, Tampa, FL, USA.
authors.forename: Ritin
authors.identifier: 0000-0001-8365-9916
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Department of Geoscience, University of Calgary, Calgary, AB, Canada.|Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Emmo
authors.initials: E
authors.lastname: Hamann
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Theresa
authors.initials: T
authors.lastname: Hargesheimer
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.|Nordic Center for Earth Evolution, University of Southern Denmark, Odense, Denmark.
authors.forename: Beate
authors.initials: B
authors.lastname: Kraft
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Lenk
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.|NIOZ Royal Netherlands Institute for Sea Research, Yerseke, The Netherlands.
authors.forename: Jeanine S
authors.initials: JS
authors.lastname: Geelhoed
authors.affiliation: Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.|UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hettich
authors.affiliation: Department of Geoscience, University of Calgary, Calgary, AB, Canada.|Max Planck Institute for Marine Microbiology, Bremen, Germany.|Institute for Genome Research and Systems Biology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Strous
mesh_terms: D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry* / Q000382:microbiology*; D056186:Metagenomics; D010084:Oxidation-Reduction; D010100:Oxygen; D010101:Oxygen Consumption
chemical_list: D010100:Oxygen