Evaluation of Reductive Release as a Mechanism for Iron Uptake from Ferrioxamine B by Chlorella vulgaris

The involvement of ferric reduction in the iron uptake mechanism of iron-stressed Chlorella vulgaris from ferrioxamine B was investigated. Some comparative data for ferric-citrate was also obtained. EPR and a spectrophotometric assay were used to measure Fe(3+) reduction. These two methods differed in the absolute quantity but not in effectors of ferric reduction. The mechanism governing ferric reduction was investigated by use of respiratory inhibitors, uncouplers, alternative electron acceptors, and ATPase inhibitors. Reduction appears to play a role in iron uptake from both Fe(3+)-deferrioxamine B and Fe(3+)-citrate; however, the involvement of photoreduction in Fe(3+)-citrate uptake implies multiple reductive mechanisms could be involved.