U(VI) reduction by spores of Clostridium acetobutylicum

Vecchia, Elena Dalla; Veeramani, Harish; Suvorova, Elena I.; Wigginton, Nicholas S.; Bargar, John R.; Bernier‐Latmani, Rizlan

doi:10.1016/j.resmic.2010.08.001

Cited by 34 publications

(12 citation statements)

References 26 publications

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“…U precipitates also appear in close proximity to the exosporium-like surface, the outermost shell surrounding the mature spore ( Fig. 5F and S4); this proximity is consistent with what Dalla Vecchia et al (2010) observed in batch tests of U(VI) reduction by spores of Clostridium acetobutylicum.…”

Section: 3supporting

confidence: 88%

Uranium removal and microbial community in a H 2 -based membrane biofilm reactor

et al. 2014

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Section: 3supporting

confidence: 88%

Uranium removal and microbial community in a H 2 -based membrane biofilm reactor

et al. 2014

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“…These include reductive precipitation by outer membrane cytochromes, conductive pili, or spores (6)(7)(8)(9)(10), surface adsorption by exopolysaccharide (EPS) or S-layers (9,11), or precipitation with phosphate (4,5,12,13). However, mechanisms used by cells for combating internal U toxicity are poorly understood (14).…”

mentioning

confidence: 99%

Transposon Mutagenesis Paired with Deep Sequencing of Caulobacter crescentus under Uranium Stress Reveals Genes Essential for Detoxification and Stress Tolerance

et al. 2015

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The ubiquitous aquatic bacterium Caulobacter crescentus is highly resistant to uranium (U) and facilitates U biomineralization and thus holds promise as an agent of U bioremediation. To gain an understanding of how C. crescentus tolerates U, we employed transposon (Tn) mutagenesis paired with deep sequencing (Tn-seq) in a global screen for genomic elements required for U resistance. Of the 3,879 annotated genes in the C. crescentus genome, 37 were found to be specifically associated with fitness under U stress, 15 of which were subsequently tested through mutational analysis. Systematic deletion analysis revealed that mutants lacking outer membrane transporters (rsaF a and rsaF b ), a stress-responsive transcription factor (cztR), or a ppGpp synthetase/hydrolase (spoT) exhibited a significantly lower survival rate under U stress. RsaF a and RsaF b , which are homologues of TolC in Escherichia coli, have previously been shown to mediate S-layer export. Transcriptional analysis revealed upregulation of rsaF a and rsaF b by 4-and 10-fold, respectively, in the presence of U. We additionally show that rsaF a mutants accumulated higher levels of U than the wild type, with no significant increase in oxidative stress levels. Our results suggest a function for RsaF a and RsaF b in U efflux and/or maintenance of membrane integrity during U stress. In addition, we present data implicating CztR and SpoT in resistance to U stress. Together, our findings reveal novel gene targets that are key to understanding the molecular mechanisms of U resistance in C. crescentus. IMPORTANCECaulobacter crescentus is an aerobic bacterium that is highly resistant to uranium (U) and has great potential to be used in U bioremediation, but its mechanisms of U resistance are poorly understood. We conducted a Tn-seq screen to identify genes specifically required for U resistance in C. crescentus. The genes that we identified have previously remained elusive using other omics approaches and thus provide significant insight into the mechanisms of U resistance by C. crescentus. In particular, we show that outer membrane transporters RsaF a and RsaF b , previously known as part of the S-layer export machinery, may confer U resistance by U efflux and/or by maintaining membrane integrity during U stress. U ranium (U) contamination is widespread and poses significant concerns for environmental ecology and human health (1). Chemical and physical techniques for waste treatment or removal of U are challenging and expensive. A promising, microbially mediated method for U remediation, in situ U immobilization, is more cost-effective and environmentally friendly than conventional approaches (2). If we seek to task microbes with the cleanup of contaminated sites, an understanding of how microbes defend against U toxicity is crucial. Understanding these mechanisms is necessary for the optimization of strains intended for use as U biosensors (3) or for the purpose of bioremediation (2, 4, 5).A great deal is known about various strategies used by microbes...

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“…Recently, a study has reported that spores of C. acetobutylicum DSM 792 can carry out reduction of U (138).…”

Section: Clostridium Acetobutylicummentioning

confidence: 99%

“…4). Using X-ray absorption near edge structure (XANES), Vecchia et al (138) verified that the product of U reduction was U(IV) instead of U removal being due to U(VI) precipitation or adsorption.…”

Section: Clostridium Acetobutylicummentioning

confidence: 99%

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The Role of Bacterial Spores in Metal Cycling and Their Potential Application in Metal Contaminant Bioremediation

2016

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Bacteria are one of the premier biological forces that, in combination with chemical and physical forces, drive metal availability in the environment. Bacterial spores, when found in the environment, are often considered to be dormant and metabolically inactive, in a resting state waiting for favorable conditions for them to germinate. However, this is a highly oversimplified view of spores in the environment. The surface of bacterial spores represents a potential site for chemical reactions to occur. Additionally, proteins in the outer layers (spore coats or exosporium) may also have more specific catalytic activity. As a consequence, bacterial spores can play a role in geochemical processes and may indeed find uses in various biotechnological applications. The aim of this review is to introduce the role of bacteria and bacterial spores in biogeochemical cycles and their potential use as toxic metal bioremediation agents.

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U(VI) reduction by spores of Clostridium acetobutylicum

Cited by 34 publications

References 26 publications

Uranium removal and microbial community in a H 2 -based membrane biofilm reactor

Uranium removal and microbial community in a H 2 -based membrane biofilm reactor

Transposon Mutagenesis Paired with Deep Sequencing of Caulobacter crescentus under Uranium Stress Reveals Genes Essential for Detoxification and Stress Tolerance

The Role of Bacterial Spores in Metal Cycling and Their Potential Application in Metal Contaminant Bioremediation

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