[word=Fe] [lemma="("] [tag=CD] [□=□]
[word=Fe] [lemma="("] [tag=CD] [word=□]
[word=Fe] [lemma="("] [tag=CD] [tag=□]
Inorganic Fe ( III ) and siderophore-bound Fe ( III ) were more bioavailable to Trichodesmium colonies than was porphyrin-bound Fe ( III ) . We conducted Fe uptake experiments using model ligands labeled with 55Fe to compare the bioavailability of inorganic Fe ( III ) , porphyrin-bound Fe ( III ) , and siderophorebound Fe ( III ) to field-collected Trichodesmium colonies . This iron is formally oxidized to Fe ( V ) in the oxidation-reduction cycle , although spectroscopic evidence suggests that Complex I is more likely to be an Fe ( IV ) - porphyrin cation ( 4 ) . Since Fe ( III ) is the oxidized form of iron under aerobic conditions , it often presents a major problem for iron-dependent organisms ( mainly poor availability ) .