Continuous time-resolved X-ray diffraction of the biocatalyzed reduction of Mn oxide

Timothy B. Fischer, Peter J. Heaney, Je Hun Jang, Daniel E. Ross, Susan Louise Brantley, Jeffrey E. Post, Ming Tien

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Here we report the first continuous time-resolved X-ray diffraction analysis of a biologically mediated mineral reaction. We incubated total membrane (TM) fractions of the facultative anaerobe Shewanella oneidensis in an anoxic environmental reaction cell with formate (as electron donor via formate dehydrogenase) and powdered birnessite, a layered Mn3+,4+ oxide common to many soils. Using both synchrotron and conventional X-ray sources, we irradiated the reaction mixtures for up to two weeks and observed bioreduction and dissolution of birnessite and the concomitant precipitation of rhodochrosite [Mn2+CO3] and hausmannite [Mn2+ Mn23+O4]. The high time resolution of these experiments documented systematic changes in crystal structure during the breakdown of birnessite and the emergence of nanocarystalline rhodochrosite. In addition, the relative abundances of birnessite and rhodochrosite were quantified over time for different concentrations of TM fraction, allowing for the determination of rate equations that govern this bioreaction. Importantly, constant irradiation for two weeks did not stop the enzymatic reaction, suggesting that enzymes may be more resilient than whole cells when exposed to X-ray radiation.

Original languageEnglish (US)
Pages (from-to)1929-1932
Number of pages4
JournalAmerican Mineralogist
Volume93
Issue number11-12
DOIs
StatePublished - Nov 1 2008

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

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