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Iron binding organic ligands

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Why is there little iron in marine environments?

Researchers investigated the reasons behind the low bioavailability of iron in seawater by determining the role of bacteria-related processes.

Climate Change and Environment icon Climate Change and Environment

Iron is involved in many biological processes but it normally accumulates as oxides and superoxides, forms which cannot be readily utilised by microorganisms. To process iron into a soluble form, bacteria release iron scavenging molecules known as siderophores. In seawater, the iron levels are in the picomolar to nanomolar range due to its low solubility and rapid uptake by phytoplankton. Marine biologists joined forces in the EU-funded 'Iron binding organic ligands' (FeBOL) project to detect if the low iron levels found in seawater were due to siderophores. Project partners used a hydrophobic resin and a filtration technique to isolate naturally occurring iron-binding ligands and determine their chemical composition and iron concentration. Samples from contrasting marine environments were collected and processed to separate iron-ligand complexes. By combining liquid chromatography and mass spectrometry, project researchers were able to detect and extract 30 % of all natural iron-ligand complexes found in seawater. The sensitivity of this technique revealed the presence of distinct iron ligands of roughly three polarity ranges. Study results showed that the ligands identified in iron-ligand complexes affected iron uptake by phytoplankton. Overall, the FeBOL project has improved our understanding on the mechanistic pathways of siderophores and how they affect iron uptake and regulation by phytoplankton. Study findings are expected to have important implications on maintaining marine ecology.

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