Distinct siderophores contribute to iron cycling in the mesopelagic at Station ALOHA
Date
2018-03-01Author
Bundy, Randelle M.
Concept link
Boiteau, Rene M.
Concept link
McLean, Craig
Concept link
Turk-Kubo, Kendra A.
Concept link
McIlvin, Matthew R.
Concept link
Saito, Mak A.
Concept link
Van Mooy, Benjamin A. S.
Concept link
Repeta, Daniel J.
Concept link
Metadata
Show full item recordCitable URI
https://hdl.handle.net/1912/10328As published
https://doi.org/10.3389/fmars.2018.00061DOI
10.3389/fmars.2018.00061Keyword
Iron; Siderophores; Station ALOHA; Organic ligands; Iron limitationAbstract
The distribution of dissolved iron (Fe), total organic Fe-binding ligands, and siderophores were measured between the surface and 400 m at Station ALOHA, a long term ecological study site in the North Pacific Subtropical Gyre. Dissolved Fe concentrations were low throughout the water column and strong organic Fe-binding ligands exceeded dissolved Fe at all depths; varying from 0.9 nmol L−1 in the surface to 1.6 nmol L−1 below 150 m. Although Fe does not appear to limit microbial production, we nevertheless found siderophores at nearly all depths, indicating some populations of microbes were responding to Fe stress. Ferrioxamine siderophores were most abundant in the upper water column, with concentrations between 0.1 and 2 pmol L−1, while a suite of amphibactins were found below 200 m with concentrations between 0.8 and 11 pmol L−1. The distinct vertical distribution of ferrioxamines and amphibactins may indicate disparate strategies for acquiring Fe from dust in the upper water column and recycled organic matter in the lower water column. Amphibactins were found to have conditional stability constants (log KcondFeL1,Fe′) ranging from 12.0 to 12.5, while ferrioxamines had much stronger conditional stability constants ranging from 14.0 to 14.4, within the range of observed L1 ligands by voltammetry. We used our data to calculate equilibrium Fe speciation at Station ALOHA to compare the relative concentration of inorganic and siderophore complexed Fe. The results indicate that the concentration of Fe bound to siderophores was up to two orders of magnitude higher than inorganic Fe, suggesting that even if less bioavailable, siderophores were nevertheless a viable pathway for Fe acquisition by microbes at our study site. Finally, we observed rapid production of ferrioxamine E by particle-associated bacteria during incubation of freshly collected sinking organic matter. Fe-limitation may therefore be a factor in regulating carbon metabolism and nutrient regeneration in the mesopelagic.
Description
© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Marine Science 5 (2018): 61, doi:10.3389/fmars.2018.00061.
Collections
Suggested Citation
Frontiers in Marine Science 5 (2018): 61The following license files are associated with this item:
Related items
Showing items related by title, author, creator and subject.
-
Trichodesmium sample provenance from samples collected in North Atlantic surface waters, station BATS, and station ALOHA between 2000 and 2018
Saito, Mak A. (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2020-04-02)Trichodesmium sample provenance collected in North Atlantic surface waters, at station BATS (Bermuda Atlantic Time-series Study), and station ALOHA (A Long-Term Oligotrophic Habitat Assessment) between 2000 and 2018. For ... -
Metaproteomes of Trichodesmium from samples collected in North Atlantic surface waters, station BATS, and station ALOHA between 2000 and 2018
Held, Noelle; Saito, Mak A. (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2020-04-29)Metaproteomes of Trichodesmium from samples collected in North Atlantic surface waters, at station BATS (Bermuda Atlantic Time-series Study), and station ALOHA (A Long-Term Oligotrophic Habitat Assessment) between 2000 and ... -
Polyphosphate dynamics at Station ALOHA, North Pacific subtropical gyre
Diaz, Julia M.; Björkman, Karin M.; Haley, Sheean T.; Ingall, Ellery; Karl, David M.; Longo, Amelia; Dyhrman, Sonya T. (John Wiley & Sons, 2015-10-27)Polyphosphate (polyP) was examined within the upper water column (≤ 150 m) of Station ALOHA (22° 45′N, 158° 00′W) during two cruises conducted in May–June 2013 and September 2013. Phosphorus molar ratios of particulate ...