Mixed-valence cytoplasmic iron granules are linked to anaerobic respiration

Intracellular granules containing ferric and ferrous iron formed in Shewanella putrefaciens CN32 during dissimilatory reduction of solid-phase ferric iron. It is the first in situ detection at high resolution (150 nm) of a mixed-valence metal particle residing within a prokaryotic cell. The relationship of the internal particles to Fe(III) reduction may indicate a respiratory role.