Single-Cell Imaging and Spectroscopic Analyses of Cr(VI) Reduction on the Surface of Bacterial Cells

Wang, Yuanmin; Sevinç, Papatya C.; Belchik, Sara M.; Fredrickson, Jim K.; Shi, Liang; Lu, H. Peter

doi:10.1021/la303779y

Cited by 42 publications

(22 citation statements)

References 39 publications

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“…The presence of a chromium hydroxide- or oxide-like phase has been documented previously in the bioreduction of Cr 6+ by Flexivirga alba ST13 T , based on a comparative analysis of XANES spectra of Cr(OH) 3 and the Cr-precipitate (Sugiyama et al, 2012). Similarly, Cr 2 O 3 nanoparticles were produced and adsorbed on the cell surface of S. oneidensis MR-1 during the bioreduction of Cr 6+ and its chemical nature was confirmed by energy dispersive spectroscopy imaging and Raman spectroscopy (Wang et al, 2012). …”

Section: Discussionmentioning

confidence: 90%

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Singh

Dong

Liu

et al. 2015

Geochimica et Cosmochimica Acta

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Despite the significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70°C). In this study, Methanothermobacter thermautotrophicus, an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H2/CO2 as substrate with various Cr6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K2Cr2O7). Time-course measurements of aqueous Cr6+ concentrations with the 1, 5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr6+ solutions by this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr6+ to cells at this concentration range. At these higher Cr6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr6+ bioreduction rates decreased with increased initial concentrations of Cr6+ from 13.3 to1.9 µM h−1. X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr6+ to insoluble Cr3+ precipitates, which was confirmed as amorphous chromium hydroxide by X-ray diffraction and selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr3+. Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of this study demonstrate the ability of M. thermautotrophicus cells to reduce toxic Cr6+ to less toxic Cr3+ and its potential application in metal bioremediation, especially at high temperature subsurface radioactive waste disposal sites, where the temperature may reach ∼70°C.

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Section: Discussionmentioning

confidence: 90%

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Singh

Dong

Liu

et al. 2015

Geochimica et Cosmochimica Acta

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“…S5 in the supplemental material). As it has been reported that, under similar conditions, S. oneidensis MR-1 reduces dichromate to Cr(III) (19,46), we obtained the XANES spectra of Cr in the biofilms of both WT and CP2-1-S1 to examine the Cr oxidation states (Fig. 3).…”

Section: Immobilization Of Cr(vi) By Cp2-1-s1 Biofilmsmentioning

confidence: 99%

Disruption of Putrescine Biosynthesis in Shewanella oneidensis Enhances Biofilm Cohesiveness and Performance in Cr(VI) Immobilization

Ding

Peng

et al. 2014

Appl Environ Microbiol

121

159

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Although biofilm-based bioprocesses have been increasingly used in various applications, the long-term robust and efficient biofilm performance remains one of the main bottlenecks. In this study, we demonstrated that biofilm cohesiveness and performance of Shewanella oneidensis can be enhanced through disrupting putrescine biosynthesis. Through random transposon mutagenesis library screening, one hyperadherent mutant strain, CP2-1-S1, exhibiting an enhanced capability in biofilm formation, was obtained. Comparative analysis of the performance of biofilms formed by S. oneidensis MR-1 wild type (WT) and CP2-1-S1 in removing dichromate (Cr 2 O 7 2؊ ), i.e., Cr(VI), from the aqueous phase showed that, compared with the WT biofilms, CP2-1-S1 biofilms displayed a substantially lower rate of cell detachment upon exposure to Cr(VI), suggesting a higher cohesiveness of the mutant biofilms. In addition, the amount of Cr(III) immobilized by CP2-1-S1 biofilms was much larger, indicating an enhanced performance in Cr(VI) bioremediation. We further showed that speF, a putrescine biosynthesis gene, was disrupted in CP2-1-S1 and that the biofilm phenotypes could be restored by both genetic and chemical complementations. Our results also demonstrated an important role of putrescine in mediating matrix disassembly in S. oneidensis biofilms.

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“…Wang et al (2013) revealed that the cooperation of surface proteins OmcA and MtrC makes the reduction of heavy metals more efficient. They suggested that direct microbial Cr(VI) reduction and Fe(II) (hematite)-mediated Cr(VI) reduction mechanisms may co-exist in the reduction processes.…”

Section: Systems Biology Approach To Bioremediationmentioning

confidence: 99%

Biotechnological advances in bioremediation of heavy metals contaminated ecosystems: an overview with special reference to phytoremediation

Mani

Kumar

2013

Int. J. Environ. Sci. Technol.

507

137

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The ability of heavy metals bioaccumulation to cause toxicity in biological systems-human, animals, microorganisms and plants-is an important issue for environmental health and safety. Recent biotechnological approaches for bioremediation include biomineralization (mineral synthesis by living organisms or biomaterials), biosorption (dead microbial and renewable agricultural biomass), phytostabilization (immobilization in plant roots), hyperaccumulation (exceptional metal concentration in plant shoots), dendroremediation (growing trees in polluted soils), biostimulation (stimulating living microbial population), rhizoremediation (plant and microbe), mycoremediation (stimulating living fungi/mycelial ultrafiltration), cyanoremediation (stimulating algal mass for remediation) and genoremediation (stimulating gene for remediation process). The adequate restoration of the environment requires cooperation, integration and assimilation of such biotechnological advances along with traditional and ethical wisdom to unravel the mystery of nature in the emerging field of bioremediation. This review highlights better understanding of the problems associated with the toxicity of heavy metals to the contaminated ecosystems and their viable, sustainable and eco-friendly bioremediation technologies, especially the mechanisms of phytoremediation of heavy metals along with some case studies in India and abroad. However, the challenges (biosafety assessment and genetic pollution) involved in adopting the new initiatives for cleaning-up the heavy metals-contaminated ecosystems from both ecological and greener point of view must not be ignored.

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Single-Cell Imaging and Spectroscopic Analyses of Cr(VI) Reduction on the Surface of Bacterial Cells

Cited by 42 publications

References 39 publications

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Disruption of Putrescine Biosynthesis in Shewanella oneidensis Enhances Biofilm Cohesiveness and Performance in Cr(VI) Immobilization

Biotechnological advances in bioremediation of heavy metals contaminated ecosystems: an overview with special reference to phytoremediation

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