Iron limitation and the role of siderophores in marine Synechococcus
Rivers, Adam R.
MetadataShow full item record
LocationCosta Rica Upwelling Dome
Marine cyanobacteria in the genus Synechococcus are widely distributed and contribute significantly to global primary productivity. In many parts of the ocean their growth is limited by a lack of iron, an essential nutrient that is virtually insoluble in seawater. To overcome this, Synechococcus have evolved a number of strategies to acquire iron. Gene distribution, metagenomics and a novel immunological flow cytometry assay in the Costa Rica Upwelling Dome were used to estimate the importance of Fe stress. Genomic and metagenomic measures suggest that iron limitation is, paradoxically, more severe in coastal and upwelling areas than in the open ocean, where iron is less abundant. A serological assay found significant differences in the vertical distribution of the Fe stress protein IdiA over just a few meters. Despite average surface ocean iron concentrations of just 0.07 nM, most marine oligotrophic cyanobacteria lack iron-binding siderophores that are present in many heterotrophic marine bacteria. Siderophores are widely distributed in the surface ocean and compose an important portion of the pool of natural ligands that bind >99% of all soluble Fe. In bottle incubations from the Sargasso Sea we found the addition of Fe complexed to an excess of the siderophore desferrioxamine B (DFB) limited Synechococcus growth and stimulated the growth of heterotrophic bacteria in a concentration dependent manner. Laboratory work revealed that excess DFB decreased Synechococcus growth beyond Fe-limited controls at concentrations as low as 20-40 nM. The inhibition was aggravated by light but it could be reversed by the addition of Fe. The DFB inhibition could not be explained by thermodynamic or kinetic models of Fe’ or co-limitation with other metals. DFB may interact with some aspect of cellular physiology to directly inhibit cyanobacterial growth.
Submitted 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 June 2009
Suggested CitationThesis: Rivers, Adam R., "Iron limitation and the role of siderophores in marine Synechococcus", 2009-06, DOI:10.1575/1912/2973, https://hdl.handle.net/1912/2973
Showing items related by title, author, creator and subject.
Marine sedimentary organic matter : delineation of marine and terrestrial sources through radiocarbon dating; and the role of organic sulfur in early petroleum generation Benitez-Nelson, Bryan C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1996-05)This thesis details two years of research conducted with the guidance and support of three advisors: Dr. J. K. Whelan, Dr. J. S. Seewald and Dr. T. I. Eglinton. Each of the three chapters represents a different, ...
Dynamic energy budgets and bioaccumulation : a model for marine mammals and marine mammal populations Klanjscek, Tin (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2006-06)Energy intake of individuals affects growth of organisms and, therefore, populations. Persistent lipophilic toxicants acquired with the energy can bioaccumulate and harm individuals. Marine mammals are particularly ...
Developing a national marine electronics agenda : proceedings of the Marine Instrumentation Panel meeting, September 12-14, 1989 Gaines, Arthur G.; Lindborg, Kristina L. C. (Woods Hole Oceanographic Institution, 1990-12)Thirteen short papers address aspects of competitiveness in the marine electronics instrumentation industry. Topics include activity and status of government initiatives in Japan and Europe to promote this industry; and ...