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dc.contributor.authorBoiteau, Rene M.  Concept link
dc.coverage.spatial39.43°N, 124.54°W
dc.date.accessioned2016-03-08T14:40:28Z
dc.date.available2016-03-08T14:40:28Z
dc.date.issued2016-02
dc.identifier.urihttps://hdl.handle.net/1912/7837
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2016en_US
dc.description.abstractMarine microbes produce a wide variety of metal binding organic ligands that regulate the solubility and availability of biologically important metals such as iron, copper, cobalt, and zinc. In marine environments where the availability of iron limits microbial growth and carbon fixation rates, the ability to access organically bound iron confers a competitive advantage. Thus, the compounds that microbes produced to acquire iron play an important role in biogeochemical carbon and metal cycling. However, the source, abundance, and identity of these compounds are poorly understood. To investigate these processes, sensitive methodologies were developed to gain a compound-specific window into marine iron speciation by combining trace metal clean sample collection and chromatography with inductively coupled plasma mass spectrometry (LCICPMS) and electrospray ionization mass spectrometry (LC-ESIMS). Coupled with isotope pattern assisted search algorithms, these tools provide a means to quantify and isolate specific iron binding ligands from seawater and marine cultures, identify them based on their mass and fragmentation spectra, and investigate their metal binding kinetics. Using these techniques, we investigated the distribution and diversity of marine iron binding ligands. In cultures, LC-ICPMS-ESIMS was used to identify new members of siderophore classes produced by marine cyanobacteria and heterotrophic bacteria, including synechobactins and marinobactins. Applications to natural seawater samples from the Pacific Ocean revealed a wide diversity of both known and novel metal compounds that are linked to specific nutrient regimes. Ferrioxamines B, E, and G were identified in productive coastal waters near California and Peru, in oligotrophic waters of the North and South Pacific Gyre, and in association with zooplankton grazers. Siderophore concentrations were up to five-fold higher in iron-deficient offshore waters (9pM) and were dominated by amphibactins, amphiphilic siderophores that partition into cell membranes. Furthermore, synechobactins were detected within nepheloid layers along the continental shelf. These siderophores reflect adaptations that impact dissolved iron bioavailability and thus have important consequences for marine ecosystem community structures and primary productivity. The ability to map and characterize these compounds has opened new opportunities to better understand mechanisms that link metals with the microbes that use them.en_US
dc.description.sponsorshipThanks to the National Science Foundation Graduate Research Fellowship Program (NSF Award 0645960) for providing three years of funding. A special thanks to the National Science Foundation Chemical Oceanography Program (NSF awards OCE-01751733 and OCE-1356747) and the Gordon and Betty Moore Foundation for providing research and instrumentation funding that made this work possible. Additional support was provided by the Center for Microbial Oceanography: Research and Education (CMORE IF0424599) and the Simons Collaboration on Ocean Processes and Ecology (SCOPE).en_US
dc.language.isoen_USen_US
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen_US
dc.relation.ispartofseriesWHOI Thesesen_US
dc.subjectMelville (Ship) Cruise MV1405en_US
dc.subjectBiogeochemical cycles
dc.subjectMicroorganisms
dc.titleMolecular determination of marine iron ligands by mass spectrometryen_US
dc.typeThesisen_US
dc.identifier.doi10.1575/1912/7837


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