Urea and nickel utilization in marine cyanobacteria as evaluated by incubation, proteomic, and uptake techniques
Goepfert, Tyler J.
MetadataShow full item record
LocationEquatorial Pacific Upwelling
South Pacific Gyre
KeywordPrimary productivity; Nitrogen cycle; Melville (Ship) Cruise MV1015; Kilo Moana (Ship) Cruise KM1128
Nitrogen and trace metal biogeochemical effects on phytoplankton productivity were compared through whole water bottle incubations and proteomic evaluation of in situ harvested particulate matter from two distinct oceanographic regions: the Equatorial Pacific Upwelling and the South Pacific Gyre. Phytoplankton growth in both regions was stimulated by nitrogen additions with equivalent response from nitrate and urea. In the gyre, trace metal additions did not yield a chlorophyll response, however nickel treatments showed evidence of nickel-limited nitrogen fixation. In contrast, cell growth at the upwelling site was primarily iron-limited and iron plus urea or nitrate additions further enhanced the chlorophyll response, indicative of secondary nitrogen limitation. Nitrogen stress proteins and urea transporters from cyanobacteria in these field sites showed similar trends, with both increasing in waters containing lower dissolved inorganic nitrogen. Together with bottle incubations, the abundant urea transporters and nitrogen stress proteins indicate the importance of urea in these field sites. Representative cyanobacteria cultures (Synechococcus strain WH8020, and Prochlorococcus strain MED4) were evaluated to constrain urea uptake rates and explore the potential for compound specific uptake rates. Together, results from this study indicate that urea may represent an under-recognized component of the marine microbial nitrogen cycle.
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2013
Suggested CitationThesis: Goepfert, Tyler J., "Urea and nickel utilization in marine cyanobacteria as evaluated by incubation, proteomic, and uptake techniques", 2013-06, DOI:10.1575/1912/6094, https://hdl.handle.net/1912/6094
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