1. Utilization of urea and cyanate in waters overlying and within the eastern tropical north Pacific oxygen deficient zone.
- Author
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Widner B, Fuchsman CA, Chang BX, Rocap G, and Mulholland MR
- Subjects
- Ammonium Compounds metabolism, Archaea classification, Archaea genetics, Archaea metabolism, Bacteria classification, Bacteria genetics, Bacteria metabolism, Nitrogen metabolism, Oxidation-Reduction, Oxygen metabolism, Pacific Ocean, Cyanates metabolism, Oxygen analysis, Seawater chemistry, Seawater microbiology, Urea metabolism
- Abstract
In marine oxygen deficient zones (ODZs), which contribute up to half of marine N loss, microbes use nitrogen (N) for assimilatory and dissimilatory processes. Here, we examine N utilization above and within the ODZ of the Eastern Tropical North Pacific Ocean, focusing on distribution, uptake and genes for the utilization of two simple organic N compounds, urea and cyanate. Ammonium, urea and cyanate concentrations generally peaked in the oxycline while uptake rates were highest in the surface. Within the ODZ, concentrations were lower, but urea N and C and cyanate C were taken up. All identified autotrophs had an N assimilation pathway that did not require external ammonium: ODZ Prochlorococcus possessed genes to assimilate nitrate, nitrite and urea; nitrite oxidizers (Nitrospina) possessed genes to assimilate nitrite, urea and cyanate; anammox bacteria (Scalindua) possessed genes to utilize cyanate; and ammonia-oxidizing Thaumarchaeota possessed genes to utilize urea. Urease genes were present in 20% of microbes, including SAR11, suggesting the urea utilization capacity was widespread. In the ODZ core, cyanate genes were largely (∼95%) associated with Scalindua, suggesting that, within this ODZ, cyanate N is primarily used for N loss via anammox (cyanammox), and that anammox does not require ammonium for N loss.
- Published
- 2018
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