Copper complexation by siderophores from filamentous blue‐green algae1 | CU Experts

From our experimental evidence that iron limitation greatly increases the extracellular concentration of strong copper‐complexing agents in cultures of Anabaena flos‐aquae and Anabaena cylindrica, and that the iron‐algal exudate complex is much more stable than the copper complex, we conclude that strong copper‐complexing agents released by filamentous blue‐green algae are siderophores. Further experiments demonstrate that siderophore excretion is not a mechanism by which blue‐green algae overcome the toxic effects of micromolar copper additions. From estimates of concentrations of iron, copper, and siderophores in iron‐limited blue‐green algal blooms, it is predicted that the copper‐siderophore complex is the major copper species. The copper‐siderophore complex is probably not toxic and its presence in freshwaters may be advantageous to cyanophyte populations.

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