Characterization of Unknown Biogenic Organic Compounds During Dissimilatory Metal Reduction
EMSL Project ID
30508
Abstract
Dissimilatory metal-reducing bacteria (DMRB), such as Shewanella oneidensis MR-1, can generate energy by transferring electrons to insoluble Fe(III) oxides. They localize multi-heme cytochromes to the outer membrane where they can reduce metal oxides by direct cell contact. DMRB may also facilitate reduction at a distance through secretion of electron shuttles. Recent reports have also described endogenous production by Shewanella of extracellular Fe(III) chealtors and flavins, which can function as electron shuttles. These bacteria can also use exogenous electron shuttles (i.e., humic acids) to reduce Fe(III) oxides. Despite these findings, the mechanisms of extracellular metal reduction remain obscure as do the factors controlling biomineralization of poorly crystalline Fe(III) phases.In typical experiments, lactate is provided as an electron donor for metal reduction. Quantification of lactate and its metabolites, such as acetate, are routinely measured by HPLC. We have noticed an unknown compound in our organic acid analysis that increases in concentration during the course of Fe oxide reduction by Shewanella.
We have tested many compounds including organic acids, flavins and quinones to try to determine the identity of this, but have not been successful. EMSL capabilites to identify
endogenous Shewanella secretory products and metabolites during the course of metal reduction via LC/MS and LC/NMR could yield data with significant impact to current BES and ERSP projects.
Project Details
Project type
Exploratory Research
Start Date
2008-10-01
End Date
2009-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members