HR: 1330h
AN: B32A-0373    [PDF]
TI: Chromate [Cr(VI)] Reduction Kinetics With {\it Shewanella oneidensis} MR-1
AU: * Viamajala, S
EM: vsridhar@mail.wsu.edu
AF: WSU/NSF IGERT Center for Multiphase Environmental Research, Department of Chemical Engineering, Washington State University, P.O. Box 642170, Pullman, WA 99164-2710 United States
AU: Peyton, B M
EM: bmp@wsu.edu
AF: WSU/NSF IGERT Center for Multiphase Environmental Research, Department of Chemical Engineering, Washington State University, P.O. Box 642170, Pullman, WA 99164-2710 United States
AU: Petersen, J N
EM: jnp@wsu.edu
AF: WSU/NSF IGERT Center for Multiphase Environmental Research, Department of Chemical Engineering, Washington State University, P.O. Box 642170, Pullman, WA 99164-2710 United States
AU: Apel, W A
EM: WAA@inel.gov
AF: Biotechnology Department, Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-2203 United States
AB: Microbial transformation of Cr(VI) to Cr(III) is a potential technology for remediating sites contaminated with Cr(VI) since chromium, in the trivalent form, is much less soluble, mobile and toxic compared to its hexavalent form. For the successful implementation of this technology, it is important to understand the kinetics of the biotransoformation, microbial physiological conditions that enhance or decrease the reaction rate as well as the influence of other in-situ contaminants on kinetics. In the present study, using the well-known metal reducing bacterium {\it Shewanella oneidensis} MR-1 as a model microorganism, kinetic studies on Cr(VI) reduction were performed under anaerobic conditions with MR-1 grown on fumarate and nitrate as terminal electron acceptors. In addition, inhibition of Cr(VI) reduction rates was studied in the presence of nitrite, which is a potential co-contaminant present in Cr(VI) contaminated sites. Inhibition kinetic studies showed that Cr(VI) reduction is carried out by multiple mechanisms working in parallel and that some of these mechanisms are dependent on the physiological growth conditions of the culture. Based on this hypothesis of multiple Cr(VI) reduction mechanisms in MR-1, a dual enzyme model was developed to describe the kinetics of Cr(VI) reduction by two parallel mechanisms - (1) a rapid Cr(VI) reduction mechanism that was deactivated (or depleted) quickly and (2) a slower mechanism that had a constant activity and was sustainable for a longer duration. Kinetic parameters were estimated by fitting experimental data, and model fits were found to correspond very closely to quantitative observations of Cr(VI) reduction by MR-1.
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2003 Fall Meeting