Dissolved hydrogen and nitrogen fixation in the oligotrophic North Pacific Subtropical Gyre. Issue 5 (10th June 2013)

• Record Type: Journal Article
• Authors: Wilson, Samuel T.; del Valle, Daniela A.; Robidart, Julie C.; Zehr, Jonathan P.; Karl, David M.
• Is Part Of: Environmental microbiology reports. Volume 5:Issue 5(2013:Oct.)
• Page Start: 697
• Page End: 704
• Publication Date: 2013-06-10
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; Electronic journals; 579.17
• DOI: 10.1111/1758-2229.12069
• Languages: English
• ISSNs: 1758-2229

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The production of hydrogen (H<sub>2</sub>) is an inherent component of biological dinitrogen (N<sub>2</sub>) fixation, and there have been several studies quantifying H<sub>2</sub> production relative to N<sub>2</sub> fixation in cultures of diazotrophs. However, conducting the relevant measurements for a field population is more complex as shown by this study of N<sub>2</sub> fixation, H<sub>2</sub> consumption and dissolved H<sub>2</sub> concentrations in the oligotrophic North Pacific Ocean. Measurements of H<sub>2</sub> oxidation revealed microbial consumption of H<sub>2</sub> was equivalent to 1–7% of ethylene produced during the acetylene reduction assay and 11–63% of <sup>15</sup>N<sub>2</sub> assimilation on a molar scale. Varying abundances of <italic>Crocosphaera</italic> and <italic>Trichodesmium</italic> as revealed by <italic>nifH</italic> gene abundances broadly corresponded with diel changes observed in both N<sub>2</sub> fixation and H<sub>2</sub> oxidation. However, no corresponding changes were observed in the dissolved H<sub>2</sub> concentrations which remained consistently supersaturated (147–560%) relative to atmospheric equilibrium. The results from this field study allow the efficiency of H<sub>2</sub> cycling by natural populations of diazotrophs to be compared to cultured representatives. The findings indicate that dissolved H<sub>2</sub> concentrations may depend not only on the community composition of diazotrophs but also upon relevant environmental parameters such as light intensity or the presence of other H<sub>2</sub>‐metabolizing microorganisms.</p> </abstract>