Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/20046
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Transcriptionally active heterotrophic diazotrophs are widespread in the upper water column of the Arabian Sea
Authors: Bird, Clare
Wyman, Michael
Contact Email: michael.wyman@stir.ac.uk
Keywords: nifH
nitrogenase
nitrogen-fixation
reverse transcriptase-polymerase chain reaction
Issue Date: Apr-2013
Publisher: Wiley-Blackwell for Federation of European Microbiological Societies
Citation: Bird C & Wyman M (2013) Transcriptionally active heterotrophic diazotrophs are widespread in the upper water column of the Arabian Sea, FEMS Microbiology Ecology, 84 (1), pp. 189-200.
Abstract: Pelagic nitrogen fixation makes an important contribution to the fixed nitrogen budget of the world's oceans. Filamentous and unicellular cyanobacteria are significant players in this process but less is known of the potential activity of heterotrophic diazotrophs, although they are present and can be quite numerous in the nitrogen-deplete surface waters of the tropical and sub-tropical oceans. In this study we focused on the potential activity of several clades of heterotrophic nitrogen-fixers identified by phylogenetic analysis of 44 non-Trichodesmium-related, nifH (encoding the Fe-subunit of nitrogenase) clones from the Arabian Sea. Specific Northern slot blot protocols were developed to quantify nifH mRNAs from each clade and showed that two groups of Gammaproteobacteria, including the previously characterized UMB clade, and a third, novel phylotype affiliated with cluster III anaerobes, were actively expressing nitrogenase in the equatorial waters of this region. Transcripts (nifH mRNAs) from the latter clade were particularly abundant and were also detected in the suboxic waters of the oxygen minimum zone further north. Like the gammaproteobacterial groups, nifH expression by these organisms appeared to be insensitive to combined nitrogen concentrations and was readily detected in the nutrient-replete waters below the upper mixed layer as well as at shallower depths.
Type: Journal Article
URI: http://hdl.handle.net/1893/20046
DOI Link: http://dx.doi.org/10.1111/1574-6941.12049
Rights: The publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.
Affiliation: Biological and Environmental Sciences
Biological and Environmental Sciences

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