Chapter Three - Iron in Cyanobacteria

Approximately 40% of global photosynthesis is conducted by phytoplankton in aquatic environments. Cyanobacteria, Gram-negative photoautotrophic prokaryotes, contribute significantly to this fraction and require large amounts of the essential micronutrient iron in order to maintain their Fe-rich photosynthetic apparatus. Cyanobacterial iron requirements exceed non-photosynthetic prokaryotes by similar to 10-fold and are exceptionally high even among other photosynthetic organisms. The genomes of cyanobacterial species code for a multitude of iron transporters, iron storage complexes and iron-responsive elements involved in maintaining homeostasis in a highly variable environment. In this chapter, we will review iron transport strategies, the maintenance of intracellular homeostasis and iron limitation responses of cyanobacteria while taking into account the chemistry and environmental bioavailability of iron species.