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Title: Denitrification versus respiratory ammonification: environmental controls of two competing dissimilatory NO 3 /NO 2 reduction pathways in Shewanella loihica strain PV-4

Denitrification and respiratory ammonification are two competing, energy-conserving NO 3 /NO 2 reduction pathways that have major biogeochemical consequences for N retention, plant growth and climate. Batch and continuous culture experiments using Shewanella loihica strain PV-4, a bacterium possessing both the denitrification and respiratory ammonification pathways, revealed factors that determine NO 3 /NO 2 fate. Denitrification dominated at low carbon-to-nitrogen (C/N) ratios (that is, electron donor-limiting growth conditions), whereas ammonium was the predominant product at high C/N ratios (that is, electron acceptor-limiting growth conditions). pH and temperature also affected NO 3 /NO 2 fate, and incubation above pH 7.0 and temperatures of 30 °C favored ammonium formation. Reverse-transcriptase real-time quantitative PCR analyses correlated the phenotypic observations with nirK and nosZ transcript abundances that decreased up to 1600-fold and 27-fold, respectively, under conditions favoring respiratory ammonification. Of the two nrfA genes encoded on the strain PV-4 genome, nrfA 0844 transcription decreased only when the chemostat reactor received medium with the lowest C/N ratio of 1.5, whereas nrfA 0505 transcription occurred at low levels (≤3.4 × 10 –2 transcripts per cell) under all growth conditions. At intermediate C/N ratios, denitrification and respiratory ammonification occurred concomitantly, and both nrfA 0844more » (5.5 transcripts per cell) and nirK (0.88 transcripts per cell) were transcribed. Furthermore recent findings suggest that organisms with both the denitrification and respiratory ammonification pathways are not uncommon in soil and sediment ecosystems, and strain PV-4 offers a tractable experimental system to explore regulation of dissimilatory NO 3 /NO 2 reduction pathways.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4]
  1. Univ. of Tennessee, Knoxville, TN (United States); Korea Advanced Institute of Science and Technology, Daejeon (Korea)
  2. Georgia Inst. of Technology, Atlanta, GA (United States)
  3. Univ. of Illinois, Urbana, IL (United States)
  4. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
The ISME Journal
Additional Journal Information:
Journal Volume: 9; Journal Issue: 5; Journal ID: ISSN 1751-7362
Publisher:
Nature Publishing Group
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1471952

Yoon, Sukhwan, Cruz-García, Claribel, Sanford, Robert, Ritalahti, Kirsti M., and Löffler, Frank E.. Denitrification versus respiratory ammonification: environmental controls of two competing dissimilatory NO3–/NO2– reduction pathways in Shewanella loihica strain PV-4. United States: N. p., Web. doi:10.1038/ismej.2014.201.
Yoon, Sukhwan, Cruz-García, Claribel, Sanford, Robert, Ritalahti, Kirsti M., & Löffler, Frank E.. Denitrification versus respiratory ammonification: environmental controls of two competing dissimilatory NO3–/NO2– reduction pathways in Shewanella loihica strain PV-4. United States. doi:10.1038/ismej.2014.201.
Yoon, Sukhwan, Cruz-García, Claribel, Sanford, Robert, Ritalahti, Kirsti M., and Löffler, Frank E.. 2014. "Denitrification versus respiratory ammonification: environmental controls of two competing dissimilatory NO3–/NO2– reduction pathways in Shewanella loihica strain PV-4". United States. doi:10.1038/ismej.2014.201. https://www.osti.gov/servlets/purl/1471952.
@article{osti_1471952,
title = {Denitrification versus respiratory ammonification: environmental controls of two competing dissimilatory NO3–/NO2– reduction pathways in Shewanella loihica strain PV-4},
author = {Yoon, Sukhwan and Cruz-García, Claribel and Sanford, Robert and Ritalahti, Kirsti M. and Löffler, Frank E.},
abstractNote = {Denitrification and respiratory ammonification are two competing, energy-conserving NO3–/NO2– reduction pathways that have major biogeochemical consequences for N retention, plant growth and climate. Batch and continuous culture experiments using Shewanella loihica strain PV-4, a bacterium possessing both the denitrification and respiratory ammonification pathways, revealed factors that determine NO3–/NO2– fate. Denitrification dominated at low carbon-to-nitrogen (C/N) ratios (that is, electron donor-limiting growth conditions), whereas ammonium was the predominant product at high C/N ratios (that is, electron acceptor-limiting growth conditions). pH and temperature also affected NO3–/NO2– fate, and incubation above pH 7.0 and temperatures of 30 °C favored ammonium formation. Reverse-transcriptase real-time quantitative PCR analyses correlated the phenotypic observations with nirK and nosZ transcript abundances that decreased up to 1600-fold and 27-fold, respectively, under conditions favoring respiratory ammonification. Of the two nrfA genes encoded on the strain PV-4 genome, nrfA0844 transcription decreased only when the chemostat reactor received medium with the lowest C/N ratio of 1.5, whereas nrfA0505 transcription occurred at low levels (≤3.4 × 10–2 transcripts per cell) under all growth conditions. At intermediate C/N ratios, denitrification and respiratory ammonification occurred concomitantly, and both nrfA0844 (5.5 transcripts per cell) and nirK (0.88 transcripts per cell) were transcribed. Furthermore recent findings suggest that organisms with both the denitrification and respiratory ammonification pathways are not uncommon in soil and sediment ecosystems, and strain PV-4 offers a tractable experimental system to explore regulation of dissimilatory NO3–/NO2– reduction pathways.},
doi = {10.1038/ismej.2014.201},
journal = {The ISME Journal},
number = 5,
volume = 9,
place = {United States},
year = {2014},
month = {10}
}

Works referenced in this record:

Acetylene inhibition of nitrous oxide reduction and measurement of denitrification and nitrogen fixation in soil
journal, January 1977