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Nitrogen fixation and nitrogenase (nifH) expression in tropical waters of the eastern North Atlantic

Nitrogen fixation and nitrogenase (nifH) expression in tropical waters of the eastern North Atlantic
Nitrogen fixation and nitrogenase (nifH) expression in tropical waters of the eastern North Atlantic

Expression of nifH in 28 surface water samples collected during fall 2007 from six stations in the vicinity of the Cape Verde Islands (north-east Atlantic) was examined using reverse transcription-polymerase chain reaction (RT-PCR)-based clone libraries and quantitative RT-PCR (RT-qPCR) analysis of seven diazotrophic phylotypes. Biological nitrogen fixation (BNF) rates and nutrient concentrations were determined for these stations, which were selected based on a range in surface chlorophyll concentrations to target a gradient of primary productivity. BNF rates greater than 6 nmolNl-1 h -1 were measured at two of the near-shore stations where high concentrations of Fe and PO43- were also measured. Six hundred and five nifH transcripts were amplified by RT-PCR, of which 76% are described by six operational taxonomic units, including Trichodesmium and the uncultivated UCYN-A, and four non-cyanobacterial diazotrophs that clustered with uncultivated Proteobacteria. Although all five cyanobacterial phylotypes quantified in RT-qPCR assays were detected at different stations in this study, UCYN-A contributed most significantly to the pool of nifH transcripts in both coastal and oligotrophic waters. A comparison of results from RT-PCR clone libraries and RT-qPCR indicated that a γ-proteobacterial phylotype was preferentially amplified in clone libraries, which underscores the need to use caution interpreting clone-library-based nifH studies, especially when considering the importance of uncultivated proteobacterial diazotrophs.

Atlantic, Cape Verde, molecular, nifH, nitrogen fixation, nitrogenase
1751-7362
1201-1212
Turk, Kendra A.
d5b704ff-5468-4b38-a3b5-3fae7402cc67
Rees, Andrew P.
5971ea8f-f7ee-4556-b8b2-8ffc4b52d2c5
Zehr, Jonathan P.
df07e726-0814-4247-8a74-942c07bd23e2
Pereira, Nicole
7eeae0f5-606b-4ea5-b25c-633dd018e584
Swift, Paul
8c043fd3-42c5-45f6-ba4e-9b05e0091bad
Shelley, Rachel
237387ff-444d-428d-b5d2-79e3a4667e05
Lohan, Maeve
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Woodward, E. Malcolm S
3a11b7bf-b110-448a-b1ee-ae1ce7d0fef5
Gilbert, Jack
91a2a4ef-d70f-4160-acca-cc72ceeb2f4b
Turk, Kendra A.
d5b704ff-5468-4b38-a3b5-3fae7402cc67
Rees, Andrew P.
5971ea8f-f7ee-4556-b8b2-8ffc4b52d2c5
Zehr, Jonathan P.
df07e726-0814-4247-8a74-942c07bd23e2
Pereira, Nicole
7eeae0f5-606b-4ea5-b25c-633dd018e584
Swift, Paul
8c043fd3-42c5-45f6-ba4e-9b05e0091bad
Shelley, Rachel
237387ff-444d-428d-b5d2-79e3a4667e05
Lohan, Maeve
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Woodward, E. Malcolm S
3a11b7bf-b110-448a-b1ee-ae1ce7d0fef5
Gilbert, Jack
91a2a4ef-d70f-4160-acca-cc72ceeb2f4b

Turk, Kendra A., Rees, Andrew P., Zehr, Jonathan P., Pereira, Nicole, Swift, Paul, Shelley, Rachel, Lohan, Maeve, Woodward, E. Malcolm S and Gilbert, Jack (2011) Nitrogen fixation and nitrogenase (nifH) expression in tropical waters of the eastern North Atlantic. The ISME Journal, 5 (7), 1201-1212. (doi:10.1038/ismej.2010.205).

Record type: Article

Abstract

Expression of nifH in 28 surface water samples collected during fall 2007 from six stations in the vicinity of the Cape Verde Islands (north-east Atlantic) was examined using reverse transcription-polymerase chain reaction (RT-PCR)-based clone libraries and quantitative RT-PCR (RT-qPCR) analysis of seven diazotrophic phylotypes. Biological nitrogen fixation (BNF) rates and nutrient concentrations were determined for these stations, which were selected based on a range in surface chlorophyll concentrations to target a gradient of primary productivity. BNF rates greater than 6 nmolNl-1 h -1 were measured at two of the near-shore stations where high concentrations of Fe and PO43- were also measured. Six hundred and five nifH transcripts were amplified by RT-PCR, of which 76% are described by six operational taxonomic units, including Trichodesmium and the uncultivated UCYN-A, and four non-cyanobacterial diazotrophs that clustered with uncultivated Proteobacteria. Although all five cyanobacterial phylotypes quantified in RT-qPCR assays were detected at different stations in this study, UCYN-A contributed most significantly to the pool of nifH transcripts in both coastal and oligotrophic waters. A comparison of results from RT-PCR clone libraries and RT-qPCR indicated that a γ-proteobacterial phylotype was preferentially amplified in clone libraries, which underscores the need to use caution interpreting clone-library-based nifH studies, especially when considering the importance of uncultivated proteobacterial diazotrophs.

Full text not available from this repository.

More information

Published date: July 2011
Keywords: Atlantic, Cape Verde, molecular, nifH, nitrogen fixation, nitrogenase

Identifiers

Local EPrints ID: 414023
URI: https://eprints.soton.ac.uk/id/eprint/414023
ISSN: 1751-7362
PURE UUID: 2b3c36d2-5b63-4c23-9449-ddf8514c62b6

Catalogue record

Date deposited: 12 Sep 2017 16:32
Last modified: 13 Mar 2019 20:11

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