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Title: Molybdenum-Based Diazotrophy in a Sphagnum Peatland in Northern Minnesota

Abstract

We present that Microbial N 2 fixation (diazotrophy) represents an important nitrogen source to oligotrophic peatland ecosystems, which are important sinks for atmospheric CO 2 and are susceptible to the changing climate. The objectives of this study were (i) to determine the active microbial group and type of nitrogenase mediating diazotrophy in an ombrotrophic Sphagnum-dominated peat bog (the S1 peat bog, Marcell Experimental Forest, Minnesota, USA); and (ii) to determine the effect of environmental parameters (light, O 2, CO 2, and CH 4) on potential rates of diazotrophy measured by acetylene (C 2H 2) reduction and 15N 2incorporation. A molecular analysis of metabolically active microbial communities suggested that diazotrophy in surface peat was primarily mediated by Alphaproteobacteria (15N 2 was suppressed 90% by O 2 and 55% by C 2H 2 and was unaffected by CH 4 and CO 2 amendments. These results suggest that peatland diazotrophy is mediated by a combination of C 2H 2-sensitive and C 2H 2-insensitive microbes that are more active at low concentrations of O 2 and show similar activity at high and low concentrations of CH 4. Importance: Previous studies indicate that diazotrophy provides an important nitrogen source and is linked to methanotrophy inmore » Sphagnum-dominated peatlands. However, the environmental controls and enzymatic pathways of peatland diazotrophy, as well as the metabolically active microbial populations that catalyze this process, remain in question. In conclusion, our findings indicate that oxygen levels and photosynthetic activity override low nutrient availability in limiting diazotrophy and that members of the Alphaproteobacteria (Rhizobiales) catalyze this process at the bog surface using the molybdenum-based form of the nitrogenase enzyme.« less

Authors:
 [1];  [2];  [2];  [1];  [2];  [3];  [4];  [5];  [5];  [6]; ORCiD logo [6]
  1. Georgia Inst. of Technology, Atlanta, GA (United States). School of Earth and Atmospheric Sciences
  2. Georgia Inst. of Technology, Atlanta, GA (United States). School of Biological Sciences
  3. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences Directorate
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Divison
  6. Georgia Inst. of Technology, Atlanta, GA (United States). School of Earth and Atmospheric Sciences and School of Biological Sciences
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1394354
Grant/Contract Number:
AC05-00OR22725; SC0007144; SC0012088; AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Applied and Environmental Microbiology
Additional Journal Information:
Journal Volume: 83; Journal Issue: 17; Journal ID: ISSN 0099-2240
Publisher:
American Society for Microbiology
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Alphaproteobacteria; Sphagnum; acetylene; diazotrophy; methanotrophs; molybdenum; nitrogen cycle enzymes; nitrogen fixation; peatland; vanadium

Citation Formats

Warren, Melissa J., Lin, Xueju, Gaby, John C., Kretz, Cecilia B., Kolton, Max, Morton, Peter L., Pett-Ridge, Jennifer, Weston, David J., Schadt, Christopher W., Kostka, Joel E., and Glass, Jennifer B.. Molybdenum-Based Diazotrophy in a Sphagnum Peatland in Northern Minnesota. United States: N. p., 2017. Web. doi:10.1128/AEM.01174-17.
Warren, Melissa J., Lin, Xueju, Gaby, John C., Kretz, Cecilia B., Kolton, Max, Morton, Peter L., Pett-Ridge, Jennifer, Weston, David J., Schadt, Christopher W., Kostka, Joel E., & Glass, Jennifer B.. Molybdenum-Based Diazotrophy in a Sphagnum Peatland in Northern Minnesota. United States. doi:10.1128/AEM.01174-17.
Warren, Melissa J., Lin, Xueju, Gaby, John C., Kretz, Cecilia B., Kolton, Max, Morton, Peter L., Pett-Ridge, Jennifer, Weston, David J., Schadt, Christopher W., Kostka, Joel E., and Glass, Jennifer B.. Fri . "Molybdenum-Based Diazotrophy in a Sphagnum Peatland in Northern Minnesota". United States. doi:10.1128/AEM.01174-17. https://www.osti.gov/servlets/purl/1394354.
@article{osti_1394354,
title = {Molybdenum-Based Diazotrophy in a Sphagnum Peatland in Northern Minnesota},
author = {Warren, Melissa J. and Lin, Xueju and Gaby, John C. and Kretz, Cecilia B. and Kolton, Max and Morton, Peter L. and Pett-Ridge, Jennifer and Weston, David J. and Schadt, Christopher W. and Kostka, Joel E. and Glass, Jennifer B.},
abstractNote = {We present that Microbial N2 fixation (diazotrophy) represents an important nitrogen source to oligotrophic peatland ecosystems, which are important sinks for atmospheric CO2 and are susceptible to the changing climate. The objectives of this study were (i) to determine the active microbial group and type of nitrogenase mediating diazotrophy in an ombrotrophic Sphagnum-dominated peat bog (the S1 peat bog, Marcell Experimental Forest, Minnesota, USA); and (ii) to determine the effect of environmental parameters (light, O2, CO2, and CH4) on potential rates of diazotrophy measured by acetylene (C2H2) reduction and 15N2incorporation. A molecular analysis of metabolically active microbial communities suggested that diazotrophy in surface peat was primarily mediated by Alphaproteobacteria (15N2 was suppressed 90% by O2 and 55% by C2H2 and was unaffected by CH4 and CO2 amendments. These results suggest that peatland diazotrophy is mediated by a combination of C 2H2-sensitive and C2H2-insensitive microbes that are more active at low concentrations of O2 and show similar activity at high and low concentrations of CH4. Importance: Previous studies indicate that diazotrophy provides an important nitrogen source and is linked to methanotrophy in Sphagnum-dominated peatlands. However, the environmental controls and enzymatic pathways of peatland diazotrophy, as well as the metabolically active microbial populations that catalyze this process, remain in question. In conclusion, our findings indicate that oxygen levels and photosynthetic activity override low nutrient availability in limiting diazotrophy and that members of the Alphaproteobacteria (Rhizobiales) catalyze this process at the bog surface using the molybdenum-based form of the nitrogenase enzyme.},
doi = {10.1128/AEM.01174-17},
journal = {Applied and Environmental Microbiology},
number = 17,
volume = 83,
place = {United States},
year = {Fri Jun 30 00:00:00 EDT 2017},
month = {Fri Jun 30 00:00:00 EDT 2017}
}

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