Speaker: Rene Boiteau, Assistant Professor, CEOAS, Oregon State University
Topic: Ironing out the role of siderophores in oceanic ecosystems
Iron (Fe) is an essential nutrient for microbial growth in the oceans, impacting the carbon cycle and global marine ecosystems, but Fe does not dissolve readily in seawater and so its availability limits phytoplankton growth over much of the surface oceans. Nearly all iron dissolved in the ocean is complexed by strong organic ligands. These ligands affect the reactivity of iron, but their source and bioavailability remains poorly understood because their composition is unknown. Characterizing organic ligands has remained a formidable analytical challenge due to the complexity of organic matter in the ocean and the trace quantities of ligands and iron. To address this issue, we have developed sensitive mass spectrometry based analytical techniques for identifying and quantifying the specific organic ligands present in seawater. With these new tools, we surveyed the composition of organic ligands across the Eastern Tropical South Pacific Ocean and the California coast to evaluate the variability in ligand identity across productive marine ecosystems where bioavailable iron is scarce. Our results suggest that organic ligand composition changes predictably across the surface ocean in response to specific environmental pressures. Hydrophilic siderophores are predominantly found across regions of the ocean where iron is not expected to be the limiting nutrient for the microbial community at large. However, in regions with intense competition for iron, some microbes optimize iron acquisition by producing siderophores that minimize diffusive losses to the environment. These siderophores affect iron bioavailability and are thus likely an important component of the marine iron cycle.
Thursday, January 17, 2019 at 3:30pm to 4:30pm
Hatfield Marine Science Center, Guin Library Seminar Room
2030 SE Marine Science Dr, Newport, OR 97365