title: Nitrogen cycling. The environmental controls that govern the end product of bacterial nitrate respiration.
abstract: In the biogeochemical nitrogen cycle, microbial respiration processes compete for nitrate as an electron acceptor. Denitrification converts nitrate into nitrogenous gas and thus removes fixed nitrogen from the biosphere, whereas ammonification converts nitrate into ammonium, which is directly reusable by primary producers. We combined multiple parallel long-term incubations of marine microbial nitrate-respiring communities with isotope labeling and metagenomics to unravel how specific environmental conditions select for either process. Microbial generation time, supply of nitrite relative to nitrate, and the carbon/nitrogen ratio were identified as key environmental controls that determine whether nitrite will be reduced to nitrogenous gas or ammonium. Our results define the microbial ecophysiology of a biogeochemical feedback loop that is key to global change, eutrophication, and wastewater treatment.
authors.affiliation: Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany.
authors.forename: Beate
authors.initials: B
authors.lastname: Kraft
authors.affiliation: Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany. Institute for Genome Research and Systems Biology, Center for Biotechnology, University of Bielefeld, 33615 Bielefeld, Germany.
authors.forename: Halina E
authors.initials: HE
authors.lastname: Tegetmeyer
authors.affiliation: UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA. Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.
authors.forename: Ritin
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Department of Biological Sciences, University of North Carolina, Charlotte, NC 28223, USA. State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Klotz
authors.affiliation: Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Ferdelman
authors.affiliation: UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA. Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hettich
authors.affiliation: Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany. NIOZ Royal Netherlands Institute for Sea Research, 4401NT Yerseke, Netherlands.
authors.forename: Jeanine S
authors.initials: JS
authors.lastname: Geelhoed
authors.affiliation: Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany. Institute for Genome Research and Systems Biology, Center for Biotechnology, University of Bielefeld, 33615 Bielefeld, Germany. Department of Geoscience, University of Calgary, Calgary, Alberta T2N 1N4, Canada. mstrous@ucalgary.ca.
authors.forename: Marc
authors.initials: M
authors.lastname: Strous
mesh_terms: D000693:Anaerobiosis; D059001:Aquatic Organisms / Q000235:genetics / Q000378:metabolism*; D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D058440:Denitrification; D004777:Environment; D056186:Metagenomics; D009566:Nitrates / Q000378:metabolism*; D012623:Seawater / Q000382:microbiology*; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology
chemical_list: D009566:Nitrates; D062065:Wastewater