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Iron uptake in Chromera velia and other marine microalgae

Final Report Summary - IRONALGAE (Iron uptake in Chromera velia and other marine microalgae)

Marine microorganisms must have evolved strategies to adapt to the extremely low bioavailability of iron. However, the current understanding of the mechanisms of iron metabolism in phytoplankton remains elusive. Recently, a novel nonreductive two-step model of iron uptake was described in cells of the marine alga Chromera velia. In this project, we have compared iron requirement and iron uptake mechanism proposed for C. velia with common micro-algae belonging to different groups: Ostreococcus tauri and Micromonas pusilla (Chlorophyta), Emiliania huxleyi (Coccolithophores), Phaeodactylum tricornutum and Thalassiosira pseudonana (Diatoms). We have shown that iron binding at the cell surface is a critical step of iron uptake mechanisms in marine micro-algae and that most microalgae can take up both ferric and ferrous iron, regardless of the presence of a ferrireductase system. Using proteomic approach we identified candidate proteins involved in iron uptake/storage in O. tauri and P. tricornutum, respectively.
Furthermore, we compared ferric EDTA, ferric citrate and ferrous ascorbate as iron sources to study iron metabolism in micro-algae. While ferric EDTA is a better iron source than ferric citrate for growth and chlorophyll levels, the use of ferric citrate and ferrous ascorbate enables the molecular components that rapidly bind iron in cells of marine micro-algae to be identified.