Poster Number 14
See more from this Division: Joint Sessions
See more from this Session: Biologically Induced Dissolution and Precipitation of Minerals in Soils and Sediments (Posters)
Abstract:
The most robust method for determining crystal structures is X-ray diffraction, which is lethal to living organisms in continuous time-resolved experiments. However, recent research has shown that isolated total membrane (TM) fractions from the facultative anaerobe Shewanella oneidensis can effectively reduce Mn oxides by direct contact. We have developed a method that allows continuous monitoring of crystal structure changes in Mn oxides as a result of the reductive dissolution by bacteria. We have documented significant structural transformations as well as the precipitation of two secondary phases, rhodochrosite (MnCO3) and hausmannite (Mn3+Mn4+2O4).
The biological reduction of birnessite is characterized by a significant contraction in the unit cell volume, due primarily to a decrease in the interlayer region. This change is likely the result of Mn(IV) reduction to Mn(III) in the octahedral sheets prior to dissolution. Our experiments also show that birnessite reduction can occur rapidly in the presence of high concentrations of TM and can be completely replaced by rhodochrosite and hausmannite in three days.
See more from this Division: Joint Sessions
See more from this Session: Biologically Induced Dissolution and Precipitation of Minerals in Soils and Sediments (Posters)