The environmental controls that govern the end product of bacterial nitrate respiration

Beate Kraft, Halina E Tegetmeyer, Ritin Sharma, Martin G Klotz, Timothy G Ferdelman, Robert L Hettich, Jeanine S Geelhoed, Marc Strous

Research output: Contribution to journalJournal articleResearchpeer-review


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.

Original languageEnglish
Issue number6197
Pages (from-to)676-679
Number of pages4
Publication statusPublished - 8. Aug 2014
Externally publishedYes


  • Anaerobiosis
  • Aquatic Organisms
  • Bacteria
  • Denitrification
  • Environment
  • Metagenomics
  • Nitrates
  • Seawater
  • Waste Water
  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.


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