Single-Cell Imaging and Spectroscopic Analyses of Cr(VI) Reduction on the Surface of Bacterial Cells
| Autor: | Sara M. Belchik, James K. Fredrickson, H. Peter Lu, Liang Shi, Yuanmin Wang, Papatya C. Sevinc |
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| Rok vydání: | 2013 |
| Předmět: |
Shewanella
Surface Properties Inorganic chemistry Mutant Cytochrome c Group Reductase Spectrum Analysis Raman Redox Article symbols.namesake Chromium Compounds Electrochemistry General Materials Science Reactivity (chemistry) Shewanella oneidensis Spectroscopy biology Chemistry Wild type Spectrometry X-Ray Emission Surfaces and Interfaces Condensed Matter Physics biology.organism_classification Microscopy Electron Scanning symbols Nanoparticles Raman spectroscopy Oxidation-Reduction Nuclear chemistry |
| Zdroj: | Langmuir. 29:950-956 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la303779y |
| Popis: | We investigate single-cell reduction of toxic Cr(VI) by the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 (MR-1), an important bioremediation process, using Raman spectroscopy and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX). Our experiments indicate that the toxic and highly soluble Cr(VI) can be efficiently reduced to the less toxic and non-soluble Cr2O3 nanoparticles by MR-1. Cr2O3 is observed to emerge as nanoparticles adsorbed on the cell surface and its chemical nature is identified by EDX imaging and Raman spectroscopy. Co-localization of Cr2O3 and cytochromes by EDX imaging and Raman spectroscopy suggests a terminal reductase role for MR-1 surface-exposed cytochromes MtrC and OmcA. Our experiments revealed that the cooperation of surface proteins OmcA and MtrC makes the reduction reaction most efficient, and the sequence of the reducing reactivity of the MR-1 is: wild type > single mutant ΔmtrC or mutant ΔomcA > double mutant (ΔomcA-ΔmtrC). Moreover, our results also suggest that the direct microbial Cr(VI) reduction and Fe(II) (hematite)-mediated Cr(VI) reduction mechanisms may co-exist in the reduction processes. |
| Databáze: | OpenAIRE |
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