Project

Displacement of competing metals by iron from metal-siderophore complexes

Iron (Fe) is an essential micronutrient for plants and most microorganisms. Because the bioavailability of Fe in the external environment is often limited due the poor solubility of Fe(hydr)oxide minerals, organisms have developed Fe acquisition strategies.

Background

A key strategy involves the release of chelating ligands called siderophores (lit. "iron carriers") that increase the solubility of Fe by forming soluble Fe-siderophore complexes. The specificity of siderophores for Fe is however limited: they also form complexes with other metals in the environment, e.g. aluminium, manganese, copper, etc. Especially under conditions of low Fe bioavailability, the carbon investment involved in the production and exudation of siderophores can be considerable. A low efficiency in mobilising the target element is problematic.

This research project will examine if siderophores that are exuded for the purpose of Fe acquisition, but bind another metal are permanently lost for their purpose, or if they may exchange the competing metal for Fe and eventually still serve as an Fe transporter in the environment. This will be examined in kinetic batch experiments with suspensions of Fe(hydr)oxide minerals that are present in soils to which siderophore complexes with competing metals will be added. A range of environmental conditions (varying competing metal, pH, redox conditions, Fe mineral) will be considered. Experiments will be geared towards clearing up the mechanism of the displacement reactions. Some method development (UV-vis spectrophotometry) for analysing the siderophore speciation will also be part of the project.

Used skills

  • Literature review;
  • Proposal writing;
  • Laboratory (analytical method development, kinetic batch experiments);
  • Data processing;
  • Thesis writing.

Requirements

  • Some laboratory experience is required;
  • The required courses for:
    • MSc thesis Soil Chemistry and Chemical Soil Quality (SOC-81336);
    • Chemical Processes in Soil, Water and Atmosphere (SOC22306);
    • and preferably including Soil Quality (SOC21806)

Supervisor