Marinobacter bacteria associated with a massive sulphide ore deposit affect metal mobility in the deep subsurface

Abstract

A microorganism of the Marinobacter genus capable of Fe-oxidation at near-neutral pH, both in the presence and absence of oxygen, was found at a depth of 1.4 km in proximity to a Cu-Zn Volcanogenic Massive Sulphide (VMS) deposit, within the Triple 7 mine, Flin Flon, Manitoba, Canada. The microorganism was isolated from saline groundwater emanating from boreholes at that depth, which contained a small microbial community consisting of only two organisms. To examine biogeochemical trace metal cycling in this deep subsurface setting, incubation experiments were carried out with the Marinobacter isolate and mineralized (metal-containing ore) material in batch and column flow-through settings. The activity of the Marinobacter isolate resulted in an increase in the mobilization of major elements (Fe, S) and trace metals (Cu, Zn) from the solid ore material. These results indicate that Fe-oxidation may be an important biogeochemical process in the deep subsurface, which affects the mobilization of Fe and trace elements from buried mineralization.