Bacteria that live on iron were found for the first time at three well-known vent sites along the Mid-Atlantic Ridge. These bacteria likely play an important role in deep-ocean iron cycling, and are dominant members of communities near and adjacent to sulfur-rich hydrothermal vents prevalent along the Mid-Atlantic Ridge. This group of iron-oxidizing bacteria, Zetaproteobacteria, appears to be restricted to environments where iron is plentiful, suggesting they are highly evolved to utilize iron for energy....