Microbial imprints on sulfide minerals in submarine hydrothermal deposits

Diverse numbers of iron- and sulfur-oxidizing microbes have been found in submarine hydrothermal deposits. They have played a prominent role in weathering of seafloor sulfide deposits. However, evidence for microbe-mineral interactions in sediments is rare. Mineralogic analysis and scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX) examination of sulfide deposits from the East Pacific Rise demonstrated that (1) sulfide minerals were extensively leached, with characteristic microbial dissolution pits on mineral surfaces; (2) the possible <i>Acidithiobacillus</i>-like bacteria and metabolites were found closely associated with the dissolution pits <i>in situ</i>. The results provide direct evidence for microbial leaching on the solid mineral crystals, most likely by the contact mechanisms, in the seafloor sulfide deposits.