Alternative nitrogenase activity in the environment and nitrogen cycle implications

Xinning Zhang, Darcy L. McRose, Romain Darnajoux, J. P. Bellenger, Francois M. M. Morel, Anne M.L. Kraepiel

Research output: Contribution to journalLetter

24 Scopus citations

Abstract

Biological nitrogen fixation, the main natural input of fixed nitrogen into the biosphere, is catalyzed by Mo-, V-, or Fe-only nitrogenase metalloenzymes. Although “alternative” V- and Fe-only nitrogenase genes are found in many environments, the contribution of these isoenzymes to N2 fixation is unknown. Here we present a new method (ISARA, isotopic acetylene reduction assay) that distinguishes canonical Mo and alternative nitrogenase activities based on in vivo 13C fractionation of acetylene reduction to ethylene (13εMo = 13.1–14.7 ‰, 13εV = 7.5–8.8 ‰, 13εFe = 5.8–6.5 ‰). ISARA analyses indicate significant contributions of alternative nitrogen fixation in boreal cyanolichens and salt marshes (~10–40 % acetylene reduction, ~20–55 % N2 fixed). These results affect the quantitative interpretation of natural abundance 15N data or traditional acetylene reduction assays. They also invite a reexamination of the conditions under which the different nitrogenase isozymes are active and suggest significant interactions between the cycles of nitrogen and trace metals.

Original languageEnglish (US)
Pages (from-to)189-198
Number of pages10
JournalBiogeochemistry
Volume127
Issue number2-3
DOIs
StatePublished - Feb 1 2016

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Water Science and Technology
  • Earth-Surface Processes

Keywords

  • Alternative nitrogenase
  • Nitrogen cycle
  • Nitrogen fixation
  • Stable isotopes
  • Trace metals

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  • Cite this

    Zhang, X., McRose, D. L., Darnajoux, R., Bellenger, J. P., Morel, F. M. M., & Kraepiel, A. M. L. (2016). Alternative nitrogenase activity in the environment and nitrogen cycle implications. Biogeochemistry, 127(2-3), 189-198. https://doi.org/10.1007/s10533-016-0188-6