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Title: Denitrification by Anaeromyxobacter dehalogenans, a Common Soil Bacterium Lacking the Nitrite Reductase Genes nirS and nirK

The versatile soil bacterium Anaeromyxobacter dehalogenans lacks the hallmark denitrification genes nirS and nirK (encoding NO 2 -→NO reductases) and couples growth to NO 3 - reduction to NH 4 + (respiratory ammonification) and to N 2O reduction to N 2. A. dehalogenans also grows by reducing Fe(III) to Fe(II), which chemically reacts with NO 2 - to form N 2O (i.e., chemodenitrification). Following the addition of 100 μmol of NO 3 - or NO 2 - to Fe(III)-grown axenic cultures of A. dehalogenans, 54 (±7) μmol and 113 (±2) μmol N 2O-N, respectively, were produced and subsequently consumed. The conversion of NO 3 - to N 2 in the presence of Fe(II) through linked biotic-abiotic reactions represents an unrecognized ecophysiology of A. dehalogenans. The new findings demonstrate that the assessment of gene content alone is insufficient to predict microbial denitrification potential and N loss (i.e., the formation of gaseous N products). A survey of complete bacterial genomes in the NCBI Reference Sequence database coupled with available physiological information revealed that organisms lacking nirS or nirK but with Fe(III) reduction potential and genes for NO 3 - and N 2O reduction are not rare, indicating that NO 3 - reductionmore » to N 2 through linked biotic-abiotic reactions is not limited to A. dehalogenans. Finally, considering the ubiquity of iron in soils and sediments and the broad distribution of dissimilatory Fe(III) and NO 3 - reducers, denitrification independent of NO-forming NO 2 - reductases (through combined biotic-abiotic reactions) may have substantial contributions to N loss and N 2O flux.« less
Authors:
 [1] ;  [2] ;  [3] ; ORCiD logo [4]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Microbiology
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Biochemistry and Cellular and Molecular Biology
  3. Univ. of Illinois, Champaign, IL (United States). Dept. of Geology
  4. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Microbiology. Dept. of Civil and Environmental Engineering. Dept. of Biosystems Engineering & Soil Science. Center for Environmental Biotechnology; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; SC0006662
Type:
Accepted Manuscript
Journal Name:
Applied and Environmental Microbiology
Additional Journal Information:
Journal Volume: 84; Journal Issue: 4; Journal ID: ISSN 0099-2240
Publisher:
American Society for Microbiology
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; Anaeromyxobacter; chemodenitrification; coupled Fe- and N- redox processes; denitrification; nitrogen loss
OSTI Identifier:
1471872

Onley, Jenny R., Ahsan, Samiha, Sanford, Robert A., and Löffler, Frank E.. Denitrification by Anaeromyxobacter dehalogenans, a Common Soil Bacterium Lacking the Nitrite Reductase Genes nirS and nirK. United States: N. p., Web. doi:10.1128/AEM.01985-17.
Onley, Jenny R., Ahsan, Samiha, Sanford, Robert A., & Löffler, Frank E.. Denitrification by Anaeromyxobacter dehalogenans, a Common Soil Bacterium Lacking the Nitrite Reductase Genes nirS and nirK. United States. doi:10.1128/AEM.01985-17.
Onley, Jenny R., Ahsan, Samiha, Sanford, Robert A., and Löffler, Frank E.. 2017. "Denitrification by Anaeromyxobacter dehalogenans, a Common Soil Bacterium Lacking the Nitrite Reductase Genes nirS and nirK". United States. doi:10.1128/AEM.01985-17.
@article{osti_1471872,
title = {Denitrification by Anaeromyxobacter dehalogenans, a Common Soil Bacterium Lacking the Nitrite Reductase Genes nirS and nirK},
author = {Onley, Jenny R. and Ahsan, Samiha and Sanford, Robert A. and Löffler, Frank E.},
abstractNote = {The versatile soil bacterium Anaeromyxobacter dehalogenans lacks the hallmark denitrification genes nirS and nirK (encoding NO2-→NO reductases) and couples growth to NO3- reduction to NH4+ (respiratory ammonification) and to N2O reduction to N2. A. dehalogenans also grows by reducing Fe(III) to Fe(II), which chemically reacts with NO2- to form N2O (i.e., chemodenitrification). Following the addition of 100 μmol of NO3- or NO2- to Fe(III)-grown axenic cultures of A. dehalogenans, 54 (±7) μmol and 113 (±2) μmol N2O-N, respectively, were produced and subsequently consumed. The conversion of NO3- to N2 in the presence of Fe(II) through linked biotic-abiotic reactions represents an unrecognized ecophysiology of A. dehalogenans. The new findings demonstrate that the assessment of gene content alone is insufficient to predict microbial denitrification potential and N loss (i.e., the formation of gaseous N products). A survey of complete bacterial genomes in the NCBI Reference Sequence database coupled with available physiological information revealed that organisms lacking nirS or nirK but with Fe(III) reduction potential and genes for NO3- and N2O reduction are not rare, indicating that NO3- reduction to N2 through linked biotic-abiotic reactions is not limited to A. dehalogenans. Finally, considering the ubiquity of iron in soils and sediments and the broad distribution of dissimilatory Fe(III) and NO3- reducers, denitrification independent of NO-forming NO2- reductases (through combined biotic-abiotic reactions) may have substantial contributions to N loss and N2O flux.},
doi = {10.1128/AEM.01985-17},
journal = {Applied and Environmental Microbiology},
number = 4,
volume = 84,
place = {United States},
year = {2017},
month = {12}
}

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