title: Hydroxamate siderophores: occurrence and importance in the Atlantic Ocean.
abstract: Siderophores are chelates produced by bacteria as part of a highly specific iron uptake mechanism. They are thought to be important in the bacterial acquisition of iron in seawater and to influence iron biogeochemistry in the ocean. We have identified and quantified two types of siderophores in seawater samples collected from the Atlantic Ocean. These siderophores were identified as hydroxamate siderophores, both ferrioxamine species representative of the more soluble marine siderophores characterized to date. Ferrioxamine G was widely distributed in surface waters throughout the Atlantic Ocean, while ferrioxamine E had a more varied distribution. Total concentrations of the two siderophores were between 3 and 20 pM in the euphotic zone. If these compounds are fully complexed in seawater, they represent approximately 0.2-4.6% of the <0.2 microm iron pool. Our data confirm that siderophore-mediated iron acquisition is important for marine heterotrophic bacteria and indicate that siderophores play an important role in the oceanic biogeochemical cycling of iron.
authors.affiliation: School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, United Kingdom.
authors.forename: Edward
authors.initials: E
authors.lastname: Mawji
authors.forename: Martha
authors.initials: M
authors.lastname: Gledhill
authors.forename: James A
authors.initials: JA
authors.lastname: Milton
authors.forename: Glen A
authors.initials: GA
authors.lastname: Tarran
authors.forename: Simon
authors.initials: S
authors.lastname: Ussher
authors.forename: Anu
authors.initials: A
authors.lastname: Thompson
authors.forename: George A
authors.initials: GA
authors.lastname: Wolff
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Worsfold
authors.forename: Eric P
authors.initials: EP
authors.lastname: Achterberg
mesh_terms: D001267:Atlantic Ocean; D001419:Bacteria / Q000378:metabolism; D005290:Ferric Compounds / Q000032:analysis / Q000737:chemistry; D052836:Heterotrophic Processes; D006877:Hydroxamic Acids / Q000737:chemistry*; D007501:Iron / Q000032:analysis; D010456:Peptides, Cyclic / Q000032:analysis / Q000737:chemistry; D012623:Seawater / Q000737:chemistry; D017262:Siderophores / Q000032:analysis / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D006877:Hydroxamic Acids; D010456:Peptides, Cyclic; D017262:Siderophores; C017508:ferrioxamine E; D007501:Iron