Development of an ELISA approach for the determination of flavodoxin and ferredoxin as markers of iron deficiency in phytoplankton.

Quantification of the iron-nutritional status of phytoplankton is of great interest not only for the study of oceans but also for fresh waters. Flavodoxin is a small flavoprotein proposed as a marker for iron deficiency, since it is induced as a consequence of iron deprivation, replacing the iron-sulphur protein ferredoxin. Flavodoxin and ferredoxin have been frequently used as markers for determination of iron deficiency in phytoplankton. Using purified flavodoxin and ferredoxin from Scenedesmus vacuolatus and polyclonal antibodies against both proteins, individual ELISA tests have been developed. The assays have a linear response in the range of 30-600 ng/ml of protein.