The association of iron and manganese with bacteria on marine macroparticulate material.

Evidence of in situ metal (iron and manganese) deposition onto bacteria associated with rapidly sinking particles in the open ocean is reported. Below 100 meters, bacteria are found with extracellular capsules containing metal precipitates; the frequency of these capsules increases with depth. The capsular metal deposits appear to contribute a major portion of the weakly bound fraction of the particulate iron flux.