Alternative means of assimilating iron are surface reduction, lowering of pH, utilization of heme, or extraction of protein-complexed metal. Recent data suggest that iron-chelating molecules with similar properties to siderophores, were produced by marine bacteria under phosphate limiting growth condition. In nature phosphate binds to different type of iron minerals, and therefore it was hypothesized that bacteria can use siderophore-like molecules to dissolve such complex in order to access the phosphate.