Molecular evidence for sediment nitrogen fixation in a temperate New England estuary
Autor: | Kaitlyn R. Pritchard, Silvia E. Newell, Robinson W. Fulweiler, Sarah Q. Foster |
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Rok vydání: | 2016 |
Předmět: |
0301 basic medicine
Denitrification 030106 microbiology Heterotroph lcsh:Medicine Ecosystem Science Biology General Biochemistry Genetics and Molecular Biology Sediments 03 medical and health sciences Heterotrophic nitrogen fixation Temperate climate Marine ecosystem 14. Life underwater geography geography.geographical_feature_category nifH Ecology General Neuroscience lcsh:R Sediment Sulfate-reducing bacteria Estuary General Medicine nifH diversity Nitrogen fixation General Agricultural and Biological Sciences Bay Environmental Sciences |
Zdroj: | PeerJ, Vol 4, p e1615 (2016) PeerJ |
ISSN: | 2167-8359 |
Popis: | Primary production in coastal waters is generally nitrogen (N) limited with denitrification outpacing nitrogen fixation (N2-fixation). However, recent work suggests that we have potentially underestimated the importance of heterotrophic sediment N2-fixation in marine ecosystems. We used clone libraries to examine transcript diversity ofnifH(a gene associated with N2-fixation) in sediments at three sites in a temperate New England estuary (Waquoit Bay, Massachusetts, USA) and compared our results to net sediment N2fluxes previously measured at these sites. We observednifHexpression at all sites, including a site heavily impacted by anthropogenic N. At this N impacted site, we also observed mean net sediment N2-fixation, linking the geochemical rate measurement withnifHexpression. This same site also had the lowest diversity (non-parametric Shannon = 2.75). At the two other sites, we also detectednifHtranscripts, however, the mean N2flux indicated net denitrification. These results suggest that N2-fixation and denitrification co-occur in these sediments. Of the unique sequences in this study, 67% were most closely related to uncultured bacteria from various marine environments, 17% to Cluster III, 15% to Cluster I, and only 1% to Cluster II. These data add to the growing body of literature that sediment heterotrophic N2-fixation, even under high inorganic nitrogen concentrations, may be an important yet overlooked source of N in coastal systems. |
Databáze: | OpenAIRE |
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