Electron microscopic studies were undertak en in order to observe microorganisms on the basis of the both current hydrothermal fluid and a dead sulfides chimney's samples collected at the North Knoll of Iheya Ridge, Okinawa Trough by “Shinkai 2000” dives. As a result, both adhesive cocci and bacilli were observed in isolated or connected situation by SEM, which were recognized to adsorb S by EDX. Other studies with SEM-EDX recognized cocci and bacilli floating in the hydrothermal fluids acknowledged as “clear smokers”. These bacteria were crystallised with the elements of S and Ba. Further studies with TEM identified that bacteria adsorbed barite on the cell membrane. A range of results of microscopy sug-gest that bacteria which are considered to be S-Oxidizing Bacteria, are offering the site of producing barite.
