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Tang H, Xiang G, Xiao W, Yang Z, Zhao B. Microbial mediated remediation of heavy metals toxicity: mechanisms and future prospects. FRONTIERS IN PLANT SCIENCE 2024; 15:1420408. [PMID: 39100088 PMCID: PMC11294182 DOI: 10.3389/fpls.2024.1420408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Accepted: 06/28/2024] [Indexed: 08/06/2024]
Abstract
Heavy metal pollution has become a serious concern across the globe due to their persistent nature, higher toxicity, and recalcitrance. These toxic metals threaten the stability of the environment and the health of all living beings. Heavy metals also enter the human food chain by eating contaminated foods and cause toxic effects on human health. Thus, remediation of HMs polluted soils is mandatory and it needs to be addressed at higher priority. The use of microbes is considered as a promising approach to combat the adverse impacts of HMs. Microbes aided in the restoration of deteriorated environments to their natural condition, with long-term environmental effects. Microbial remediation prevents the leaching and mobilization of HMs and they also make the extraction of HMs simple. Therefore, in this context recent technological advancement allowed to use of bioremediation as an imperative approach to remediate polluted soils. Microbes use different mechanisms including bio-sorption, bioaccumulation, bioleaching, bio-transformation, bio-volatilization and bio-mineralization to mitigate toxic the effects of HMs. Thus, keeping in the view toxic HMs here in this review explores the role of bacteria, fungi and algae in bioremediation of polluted soils. This review also discusses the various approaches that can be used to improve the efficiency of microbes to remediate HMs polluted soils. It also highlights different research gaps that must be solved in future study programs to improve bioremediation efficency.
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Affiliation(s)
- Haiying Tang
- School of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi, China
| | - Guohong Xiang
- School of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi, China
| | - Wen Xiao
- School of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi, China
| | - Zeliang Yang
- School of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi, China
| | - Baoyi Zhao
- Shuangfeng Agriculture and Rural Bureau, Loudi, Hunan, China
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Hirth N, Wiesemann N, Krüger S, Gerlach MS, Preußner K, Galea D, Herzberg M, Große C, Nies DH. A gold speciation that adds a second layer to synergistic gold-copper toxicity in Cupriavidus metallidurans. Appl Environ Microbiol 2024; 90:e0014624. [PMID: 38557120 PMCID: PMC11022561 DOI: 10.1128/aem.00146-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 03/09/2024] [Indexed: 04/04/2024] Open
Abstract
The metal-resistant bacterium Cupriavidus metallidurans occurs in metal-rich environments. In auriferous soils, the bacterium is challenged by a mixture of copper ions and gold complexes, which exert synergistic toxicity. The previously used, self-made Au(III) solution caused a synergistic toxicity of copper and gold that was based on the inhibition of the CupA-mediated efflux of cytoplasmic Cu(I) by Au(I) in this cellular compartment. In this publication, the response of the bacterium to gold and copper was investigated by using a commercially available Au(III) solution instead of the self-made solution. The new solution was five times more toxic than the previously used one. Increased toxicity was accompanied by greater accumulation of gold atoms by the cells. The contribution of copper resistance determinants to the commercially available Au(III) solution and synergistic gold-copper toxicity was studied using single- and multiple-deletion mutants. The commercially available Au(III) solution inhibited periplasmic Cu(I) homeostasis, which is required for the allocation of copper ions to copper-dependent proteins in this compartment. The presence of the gene for the periplasmic Cu(I) and Au(I) oxidase, CopA, decreased the cellular copper and gold content. Transcriptional reporter gene fusions showed that up-regulation of gig, encoding a minor contributor to copper resistance, was strictly glutathione dependent. Glutathione was also required to resist synergistic gold-copper toxicity. The new data indicated a second layer of synergistic copper-gold toxicity caused by the commercial Au(III) solution, inhibition of the periplasmic copper homeostasis in addition to the cytoplasmic one.IMPORTANCEWhen living in auriferous soils, Cupriavidus metallidurans is not only confronted with synergistic toxicity of copper ions and gold complexes but also by different gold species. A previously used gold solution made by using aqua regia resulted in the formation of periplasmic gold nanoparticles, and the cells were protected against gold toxicity by the periplasmic Cu(I) and Au(I) oxidase CopA. To understand the role of different gold species in the environment, another Au(III) solution was commercially acquired. This compound was more toxic due to a higher accumulation of gold atoms by the cells and inhibition of periplasmic Cu(I) homeostasis. Thus, the geo-biochemical conditions might influence Au(III) speciation. The resulting Au(III) species may subsequently interact in different ways with C. metallidurans and its copper homeostasis system in the cytoplasm and periplasm. This study reveals that the geochemical conditions may decide whether bacteria are able to form gold nanoparticles or not.
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Affiliation(s)
- Niklas Hirth
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Nicole Wiesemann
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Stephanie Krüger
- Microscopy Unit, Biocenter, Martin Luther University Halle Wittenberg, Wittenberg, Germany
| | - Michelle-Sophie Gerlach
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Kilian Preußner
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Diana Galea
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Martin Herzberg
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
- Department of Analytical Chemistry, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Cornelia Große
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Dietrich H. Nies
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
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Sanyal SK, Pukala T, Mittal P, Reith F, Brugger J, Etschmann B, Shuster J. From biomolecules to biogeochemistry: Exploring the interaction of an indigenous bacterium with gold. CHEMOSPHERE 2023; 339:139657. [PMID: 37543229 DOI: 10.1016/j.chemosphere.2023.139657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 07/23/2023] [Accepted: 07/24/2023] [Indexed: 08/07/2023]
Abstract
Specialised microbial communities colonise the surface of gold particles in soils/sediments, and catalyse gold dissolution and re-precipitation, thereby contributing to the environmental mobility and toxicity of this 'inert' precious metal. We assessed the proteomic and physiological response of Serratia proteamaculans, the first metabolically active bacterium enriched and isolated directly from natural gold particles, when exposed to toxic levels of soluble Au3+ (10 μM). The results were compared to a metal-free blank, and to cultures exposed to similarly toxic levels of soluble Cu2+ (0.1 mM); Cu was chosen for comparison because it is closely associated with Au in nature due to similar geochemical properties. A total of 273 proteins were detected from the cells that experienced the oxidative effects of soluble Au, of which 139 (51%) were upregulated with either sole expression (31%) or had synthesis levels greater than the Au-free control (20%). The majority (54%) of upregulated proteins were functionally different from up-regulated proteins in the bacteria-copper treatment. These proteins were related to broad functions involving metabolism and biogenesis, followed by cellular process and signalling, indicating significant specificity for Au. This proteomic study revealed that the bacterium upregulates the synthesis of various proteins related to oxidative stress response (e.g., Monothiol-Glutaredoxin, Thiol Peroxidase, etc.) and cellular damage repair, which leads to the formation of metallic gold nanoparticles less toxic than ionic gold. Therefore, indigenous bacteria may mediate the toxicity of Au through two different yet simultaneous processes: i) repairing cellular components by replenishing damaged proteins and ii) neutralising reactive oxygen species (ROS) by up-regulating the synthesis of antioxidants. By connecting the fields of molecular bacteriology and environmental biogeochemistry, this study is the first step towards the development of biotechnologies based on indigenous bacteria applied to gold bio-recovery and bioremediation of contaminated environments.
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Affiliation(s)
- Santonu K Sanyal
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, 3800, Australia.
| | - Tara Pukala
- Adelaide Proteomics Centre, The University of Adelaide, Adelaide, South Australia, 5001, Australia; School of Physics, Chemistry and Earth Sciences, The University of Adelaide, Adelaide, South Australia, 5001, Australia
| | - Parul Mittal
- Adelaide Proteomics Centre, The University of Adelaide, Adelaide, South Australia, 5001, Australia
| | | | - Joël Brugger
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, 3800, Australia
| | - Barbara Etschmann
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, 3800, Australia
| | - Jeremiah Shuster
- Department of Earth Sciences, Western University, London, Ontario, N6A 3K7, Canada
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Hirth N, Gerlach MS, Wiesemann N, Herzberg M, Große C, Nies DH. Full Copper Resistance in Cupriavidus metallidurans Requires the Interplay of Many Resistance Systems. Appl Environ Microbiol 2023:e0056723. [PMID: 37191542 DOI: 10.1128/aem.00567-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
The metal-resistant bacterium Cupriavidus metallidurans uses its copper resistance components to survive the synergistic toxicity of copper ions and gold complexes in auriferous soils. The cup, cop, cus, and gig determinants encode as central component the Cu(I)-exporting PIB1-type ATPase CupA, the periplasmic Cu(I)-oxidase CopA, the transenvelope efflux system CusCBA, and the Gig system with unknown function, respectively. The interplay of these systems with each other and with glutathione (GSH) was analyzed. Copper resistance in single and multiple mutants up to the quintuple mutant was characterized in dose-response curves, Live/Dead-staining, and atomic copper and glutathione content of the cells. The regulation of the cus and gig determinants was studied using reporter gene fusions and in case of gig also RT-PCR studies, which verified the operon structure of gigPABT. All five systems contributed to copper resistance in the order of importance: Cup, Cop, Cus, GSH, and Gig. Only Cup was able to increase copper resistance of the Δcop Δcup Δcus Δgig ΔgshA quintuple mutant but the other systems were required to increase copper resistance of the Δcop Δcus Δgig ΔgshA quadruple mutant to the parent level. Removal of the Cop system resulted in a clear decrease of copper resistance in most strain backgrounds. Cus cooperated with and partially substituted Cop. Gig and GSH cooperated with Cop, Cus, and Cup. Copper resistance is thus the result of an interplay of many systems. IMPORTANCE The ability of bacteria to maintain homeostasis of the essential-but-toxic "Janus"-faced element copper is important for their survival in many natural environments but also in case of pathogenic bacteria in their respective host. The most important contributors to copper homeostasis have been identified in the last decades and comprise PIB1-type ATPases, periplasmic copper- and oxygen-dependent copper oxidases, transenvelope efflux systems, and glutathione; however, it is not known how all these players interact. This publication investigates this interplay and describes copper homeostasis as a trait emerging from a network of interacting resistance systems.
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Affiliation(s)
- Niklas Hirth
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | | | - Nicole Wiesemann
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Martin Herzberg
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Cornelia Große
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Dietrich H Nies
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
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Sevak P, Pushkar B, Mazumdar S. Mechanistic evaluation of chromium bioremediation in Acinetobacter junii strain b2w: A proteomic approach. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 328:116978. [PMID: 36521220 DOI: 10.1016/j.jenvman.2022.116978] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 12/01/2022] [Accepted: 12/03/2022] [Indexed: 06/17/2023]
Abstract
Growing industrialization and unchecked release of industrial waste, including heavy metals have resulted in disastrous effects on environment. Considering the problem of heavy metal pollution, the present research was designed to study the bioremediation of chromium, a highly toxic and prominent heavy metal pollutant by Acinetobacter junii strain b2w isolated from the Mithi river, Mumbai, India. The bacterial isolate could grow without affecting its growth kinetics up to a concentration of 200 ppm of chromium and showed resistance towards 400 ppm of chromium. It was able to bioremediate 83.06% of total chromium and reduces 98.24% of Cr6+ to C3+ at a concentration of 10 ppm of chromium. The bacterial isolate could grow well at a wide pH range from 5 to 9, salinity of up to 3.5% and could also tolerate heavy metals such as Cd, Zn, As, Hg, Pb and Cu. Thus, indicating its possible on-ground applicability for bioremediation of chromium. Acinetobacter junii bioaccumulate chromium without disrupting the cell integrity and biosorption. However, chromium alters the functional groups on bacterial cell surface and led to decrease in sulfate-containing molecules. Further, the protein expression study has revealed that Cr significantly up-regulates proteins broadly classified under envelope stress responses, oxidative stress responses, energy metabolism and quorum sensing and growth regulator. The possible mechanisms of Cr detoxification in Acinetobacter junii strain b2w could be reduction, bioaccumulation and efflux along with neutralization of oxidative stress generated by Cr. Thus, based on bacterial bioremediation potential and its molecular response, it can be proposed that the isolated Acinetobacter junii has potential applicability for chromium bioremediation.
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Affiliation(s)
- Pooja Sevak
- Department of Biotechnology, University of Mumbai, Santacruz (E), Mumbai, 400098, Maharashtra, India
| | - Bhupendra Pushkar
- Department of Biotechnology, University of Mumbai, Santacruz (E), Mumbai, 400098, Maharashtra, India.
| | - Shyamalava Mazumdar
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, 400005, Maharashtra, India
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Pande V, Pandey SC, Sati D, Bhatt P, Samant M. Microbial Interventions in Bioremediation of Heavy Metal Contaminants in Agroecosystem. Front Microbiol 2022; 13:824084. [PMID: 35602036 PMCID: PMC9120775 DOI: 10.3389/fmicb.2022.824084] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 03/31/2022] [Indexed: 01/09/2023] Open
Abstract
Soil naturally comprises heavy metals but due to the rapid industrialization and anthropogenic events such as uncontrolled use of agrochemicals their concentration is heightened up to a large extent across the world. Heavy metals are non-biodegradable and persistent in nature thereby disrupting the environment and causing huge health threats to humans. Exploiting microorganisms for the removal of heavy metal is a promising approach to combat these adverse consequences. The microbial remediation is very crucial to prevent the leaching of heavy metal or mobilization into the ecosystem, as well as to make heavy metal extraction simpler. In this scenario, technological breakthroughs in microbes-based heavy metals have pushed bioremediation as a promising alternative to standard approaches. So, to counteract the deleterious effects of these toxic metals, some microorganisms have evolved different mechanisms of detoxification. This review aims to scrutinize the routes that are responsible for the heavy metal(loid)s contamination of agricultural land, provides a vital assessment of microorganism bioremediation capability. We have summarized various processes of heavy metal bioremediation, such as biosorption, bioleaching, biomineralization, biotransformation, and intracellular accumulation, as well as the use of genetically modified microbes and immobilized microbial cells for heavy metal removal.
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Affiliation(s)
- Veni Pande
- Cell and Molecular Biology Laboratory, Department of Zoology (DST-FIST Sponsored), Soban Singh Jeena University Campus, Almora, India
- Department of Biotechnology, Sir J C Bose Technical Campus, Kumaun University, Bhimtal, India
| | - Satish Chandra Pandey
- Cell and Molecular Biology Laboratory, Department of Zoology (DST-FIST Sponsored), Soban Singh Jeena University Campus, Almora, India
| | - Diksha Sati
- Cell and Molecular Biology Laboratory, Department of Zoology (DST-FIST Sponsored), Soban Singh Jeena University Campus, Almora, India
- Department of Zoology, Kumaun University, Nainital, India
| | - Pankaj Bhatt
- Department of Agricultural and Biological Engineering, PurdueUniversity, West Lafayette, IN, United States
| | - Mukesh Samant
- Cell and Molecular Biology Laboratory, Department of Zoology (DST-FIST Sponsored), Soban Singh Jeena University Campus, Almora, India
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Turner RJ, Huang LN, Viti C, Mengoni A. Metal-Resistance in Bacteria: Why Care? Genes (Basel) 2020; 11:E1470. [PMID: 33302493 PMCID: PMC7764034 DOI: 10.3390/genes11121470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 12/03/2020] [Indexed: 12/27/2022] Open
Abstract
Heavy metal resistance is more than the tolerance one has towards a particular music genera [...].
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Affiliation(s)
- Raymond J. Turner
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Li-Nan Huang
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China;
| | - Carlo Viti
- Laboratorio Genexpress, Dipartimento di Scienze e Tecnologie Agrarie, Alimentari, Ambientali e Forestali, Università di Firenze, 50144 Florence, Italy;
| | - Alessio Mengoni
- Laboratorio di Genetica Microbica, Dipartimento di Biologia, Università di Firenze, 50019 Florence, Italy
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Weiland F, Lokman NA, Klingler-Hoffmann M, Jobling T, Stephens AN, Sundfeldt K, Hoffmann P, Oehler MK. Ovarian Blood Sampling Identifies Junction Plakoglobin as a Novel Biomarker of Early Ovarian Cancer. Front Oncol 2020; 10:1767. [PMID: 33102207 PMCID: PMC7545354 DOI: 10.3389/fonc.2020.01767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 08/06/2020] [Indexed: 11/28/2022] Open
Abstract
Ovarian cancer is the most lethal gynecologic malignancy. Early detection would improve survival, but an effective diagnostic test does not exist. Novel biomarkers for early ovarian cancer diagnosis are therefore warranted. We performed intraoperative blood sampling from ovarian veins of stage I epithelial ovarian carcinomas and analyzed the serum proteome. Junction plakoglobin (JUP) was found to be elevated in venous blood from ovaries with malignancies when compared to those with benign disease. Peripheral plasma JUP levels were validated by ELISA in a multicenter international patient cohort. JUP was significantly increased in FIGO serous stage IA+B (1.97-fold increase; p < 0.001; n = 20), serous stage I (2.09-fold increase; p < 0.0001; n = 40), serous stage II (1.81-fold increase, p < 0.001, n = 23) and serous stage III ovarian carcinomas (1.98-fold increase; p < 0.0001; n = 34) vs. normal controls (n = 109). JUP plasma levels were not increased in early stage breast cancer (p = 0.122; n = 12). In serous ovarian cancer patients, JUP had a sensitivity of 85% in stage IA+B and 60% in stage IA-C, with specificities of 76 and 94%, respectively. A logistic regression model of JUP and Cancer Antigen 125 (CA125) revealed a sensitivity of 70% for stage IA+B and 75% for stage IA-C serous carcinomas at 100% specificity. Our novel ovarian blood sampling – proteomics approach identified JUP as a promising new biomarker for epithelial ovarian cancer, which in combination with CA125 might fulfill the test criteria for ovarian cancer screening.
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Affiliation(s)
- Florian Weiland
- Adelaide Proteomics Centre, The University of Adelaide, Adelaide, SA, Australia.,Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA, Australia.,Department of Microbial and Molecular Systems (M2S), Laboratory of Enzyme, Fermentation and Brewing Technology (EFBT), KU Leuven, Leuven, Belgium
| | - Noor A Lokman
- Discipline of Obstetrics and Gynecology, Adelaide Medical School, Robinson Research Institute, The University of Adelaide, Adelaide, SA, Australia
| | | | - Thomas Jobling
- Department of Gynecological Oncology, Monash Medical Centre, Clayton, VIC, Australia
| | - Andrew N Stephens
- Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, VIC, Australia.,Department of Molecular and Translational Sciences, Monash University, Clayton, VIC, Australia
| | - Karin Sundfeldt
- Department of Obstetrics and Gynecology, Sahlgrenska Cancer Center, Institute of Clinical Science, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter Hoffmann
- Future Industries Institute, University of South Australia, Adelaide, SA, Australia
| | - Martin K Oehler
- Discipline of Obstetrics and Gynecology, Adelaide Medical School, Robinson Research Institute, The University of Adelaide, Adelaide, SA, Australia.,Future Industries Institute, University of South Australia, Adelaide, SA, Australia.,Department of Gynecological Oncology, Royal Adelaide Hospital, Adelaide, SA, Australia
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9
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Muñoz-Villagrán C, Contreras F, Cornejo F, Figueroa M, Valenzuela-Bezanilla D, Luraschi R, Reinoso C, Rivas-Pardo J, Vásquez C, Castro M, Arenas F. Understanding gold toxicity in aerobically-grown Escherichia coli. Biol Res 2020; 53:26. [PMID: 32513271 PMCID: PMC7278051 DOI: 10.1186/s40659-020-00292-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/16/2020] [Indexed: 12/03/2022] Open
Abstract
Background There is an emerging field to put into practice new strategies for developing molecules with antimicrobial properties. In this line, several metals and metalloids are currently being used for these purposes, although their cellular effect(s) or target(s) in a particular organism are still unknown. Here we aimed to investigate and analyze Au3+ toxicity through a combination of biochemical and molecular approaches. Results We found that Au3+ triggers a major oxidative unbalance in Escherichia coli, characterized by decreased intracellular thiol levels, increased superoxide concentration, as well as by an augmented production of the antioxidant enzymes superoxide dismutase and catalase. Because ROS production is, in some cases, associated with metal reduction and the concomitant generation of gold-containing nanostructures (AuNS), this possibility was evaluated in vivo and in vitro. Conclusions Au3+ is toxic for E. coli because it triggers an unbalance of the bacterium’s oxidative status. This was demonstrated by using oxidative stress dyes and antioxidant chemicals as well as gene reporters, RSH concentrations and AuNS generation.
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Affiliation(s)
- C Muñoz-Villagrán
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - F Contreras
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - F Cornejo
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - M Figueroa
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - D Valenzuela-Bezanilla
- Laboratorio de Microbiología Aplicada, Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad Santo Tomás, Sede Santiago, Chile
| | - R Luraschi
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - C Reinoso
- Laboratorio de Microbiología Aplicada, Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad Santo Tomás, Sede Santiago, Chile
| | - J Rivas-Pardo
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.,Laboratorio de Biología estructural, Centro de Genómica y Bioinformática, Universidad Mayor, Santiago, Chile
| | - C Vásquez
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - M Castro
- Laboratorio de Microbiología Aplicada, Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad Santo Tomás, Sede Santiago, Chile.
| | - F Arenas
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
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Sanyal SK, Reith F, Shuster J. A genomic perspective of metal-resistant bacteria from gold particles: Possible survival mechanisms during gold biogeochemical cycling. FEMS Microbiol Ecol 2020; 96:5851273. [DOI: 10.1093/femsec/fiaa111] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/02/2020] [Indexed: 11/13/2022] Open
Abstract
ABSTRACT
A bacterial consortium was enriched from gold particles that ‘experienced’ ca. 80 years of biotransformation within waste-rock piles (Australia). This bacterial consortium was exposed to 10 µM AuCl3 to obtain Au-tolerant bacteria. From these isolates, Serratia sp. and Stenotrophomonas sp. were the most Au-tolerant and reduced soluble Au as pure gold nanoparticles, indicating that passive mineralisation is a mechanism for mediating the toxic effect of soluble Au produced during particle dissolution. Genome-wide analysis demonstrated that these isolates also possessed various genes that could provide cellular defence enabling survival under heavy-metal stressed condition by mediating the toxicity of heavy metals through active efflux/reduction. Diverse metal-resistant genes or genes clusters (cop, cus, czc, zntand ars) were detected, which could confer resistance to soluble Au. Comparative genome analysis revealed that the majority of detected heavy-metal resistant genes were similar (i.e. orthologous) to those genes of Cupriavidus metallidurans CH34. The detection of heavy-metal resistance, nutrient cycling and biofilm formation genes (pgaABCD, bsmAandhmpS) may have indirect yet important roles when dealing with soluble Au during particle dissolution. In conclusion, the physiological and genomic results suggest that bacteria living on gold particles would likely use various genes to ensure survival during Au-biogeochemical cycling.
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Affiliation(s)
- Santonu Kumar Sanyal
- School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
- CSIRO Land & Water, Environmental Contaminant Mitigation and Technologies, Gate 4 Waite Road, Glen Osmond, South Australia 5064, Australia
| | - Frank Reith
- School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
- CSIRO Land & Water, Environmental Contaminant Mitigation and Technologies, Gate 4 Waite Road, Glen Osmond, South Australia 5064, Australia
| | - Jeremiah Shuster
- School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
- CSIRO Land & Water, Environmental Contaminant Mitigation and Technologies, Gate 4 Waite Road, Glen Osmond, South Australia 5064, Australia
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Mazhar SH, Herzberg M, Ben Fekih I, Zhang C, Bello SK, Li YP, Su J, Xu J, Feng R, Zhou S, Rensing C. Comparative Insights Into the Complete Genome Sequence of Highly Metal Resistant Cupriavidus metallidurans Strain BS1 Isolated From a Gold-Copper Mine. Front Microbiol 2020; 11:47. [PMID: 32117100 PMCID: PMC7019866 DOI: 10.3389/fmicb.2020.00047] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/10/2020] [Indexed: 12/12/2022] Open
Abstract
The highly heavy metal resistant strain Cupriavidus metallidurans BS1 was isolated from the Zijin gold–copper mine in China. This was of particular interest since the extensively studied, closely related strain, C. metallidurans CH34 was shown to not be only highly heavy metal resistant but also able to reduce metal complexes and biomineralizing them into metallic nanoparticles including gold nanoparticles. After isolation, C. metallidurans BS1 was characterized and complete genome sequenced using PacBio and compared to CH34. Many heavy metal resistance determinants were identified and shown to have wide-ranging similarities to those of CH34. However, both BS1 and CH34 displayed extensive genome plasticity, probably responsible for significant differences between those strains. BS1 was shown to contain three prophages, not present in CH34, that appear intact and might be responsible for shifting major heavy metal resistance determinants from plasmid to chromid (CHR2) in C. metallidurans BS1. Surprisingly, the single plasmid – pBS1 (364.4 kbp) of BS1 contains only a single heavy metal resistance determinant, the czc determinant representing RND-type efflux system conferring resistance to cobalt, zinc and cadmium, shown here to be highly similar to that determinant located on pMOL30 in C. metallidurans CH34. However, in BS1 another homologous czc determinant was identified on the chromid, most similar to the czc determinant from pMOL30 in CH34. Other heavy metal resistance determinants such as cnr and chr determinants, located on megaplasmid pMOL28 in CH34, were shown to be adjacent to the czc determinant on chromid (CHR2) in BS1. Additionally, other heavy metal resistance determinants such as pbr, cop, sil, and ars were located on the chromid (CHR2) and not on pBS1 in BS1. A diverse range of genomic rearrangements occurred in this strain, isolated from a habitat of constant exposure to high concentrations of copper, gold and other heavy metals. In contrast, the megaplasmid in BS1 contains mostly genes encoding unknown functions, thus might be more of an evolutionary playground where useful genes could be acquired by horizontal gene transfer and possibly reshuffled to help C. metallidurans BS1 withstand the intense pressure of extreme concentrations of heavy metals in its environment.
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Affiliation(s)
- Sohaib H Mazhar
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Martin Herzberg
- Molecular Microbiology, Institute for Biology/Microbiology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Ibtissem Ben Fekih
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Chenkang Zhang
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.,College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Suleiman Kehinde Bello
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuan Ping Li
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Junming Su
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Junqiang Xu
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Renwei Feng
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
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12
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Bohu T, Anand R, Noble R, Lintern M, Kaksonen AH, Mei Y, Cheng KY, Deng X, Veder JP, Bunce M, Power M, Verrall M. Evidence for fungi and gold redox interaction under Earth surface conditions. Nat Commun 2019; 10:2290. [PMID: 31123249 PMCID: PMC6533363 DOI: 10.1038/s41467-019-10006-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 04/09/2019] [Indexed: 11/11/2022] Open
Abstract
Microbial contribution to gold biogeochemical cycling has been proposed. However, studies have focused primarily on the influence of prokaryotes on gold reduction and precipitation through a detoxification-oriented mechanism. Here we show, fungi, a major driver of mineral bioweathering, can initiate gold oxidation under Earth surface conditions, which is of significance for dissolved gold species formation and distribution. Presence of the gold-oxidizing fungus TA_pink1, an isolate of Fusarium oxysporum, suggests fungi have the potential to substantially impact gold biogeochemical cycling. Our data further reveal that indigenous fungal diversity positively correlates with in situ gold concentrations. Hypocreales, the order of the gold-oxidizing fungus, show the highest centrality in the fungal microbiome of the auriferous environment. Therefore, we argue that the redox interaction between fungi and gold is critical and should be considered in gold biogeochemical cycling.
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Affiliation(s)
- Tsing Bohu
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia.
| | - Ravi Anand
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Ryan Noble
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Mel Lintern
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Anna H Kaksonen
- CSIRO Land and Water, Private Bag No.5, Wembley, WA, 6913, Australia
- School of Biomedical Sciences, University of Western Australia, Crawley, WA, 6009, Australia
| | - Yuan Mei
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Ka Yu Cheng
- CSIRO Land and Water, Private Bag No.5, Wembley, WA, 6913, Australia
- School of Engineering and Information Technology, Murdoch University, Perth, WA, 6150, Australia
| | - Xiao Deng
- CSIRO Land and Water, Private Bag No.5, Wembley, WA, 6913, Australia
| | - Jean-Pierre Veder
- John de Laeter Centre, Curtin University, Bentley, WA, 6102, Australia
| | - Michael Bunce
- Trace and Environmental DNA (TrEnD) Laboratory, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia
| | - Matthew Power
- Trace and Environmental DNA (TrEnD) Laboratory, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia
| | - Mike Verrall
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
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13
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Diep P, Mahadevan R, Yakunin AF. Heavy Metal Removal by Bioaccumulation Using Genetically Engineered Microorganisms. Front Bioeng Biotechnol 2018; 6:157. [PMID: 30420950 PMCID: PMC6215804 DOI: 10.3389/fbioe.2018.00157] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/09/2018] [Indexed: 11/25/2022] Open
Abstract
Wastewater effluents from mines and metal refineries are often contaminated with heavy metal ions, so they pose hazards to human and environmental health. Conventional technologies to remove heavy metal ions are well-established, but the most popular methods have drawbacks: chemical precipitation generates sludge waste, and activated carbon and ion exchange resins are made from unsustainable non-renewable resources. Using microbial biomass as the platform for heavy metal ion removal is an alternative method. Specifically, bioaccumulation is a natural biological phenomenon where microorganisms use proteins to uptake and sequester metal ions in the intracellular space to utilize in cellular processes (e.g., enzyme catalysis, signaling, stabilizing charges on biomolecules). Recombinant expression of these import-storage systems in genetically engineered microorganisms allows for enhanced uptake and sequestration of heavy metal ions. This has been studied for over two decades for bioremediative applications, but successful translation to industrial-scale processes is virtually non-existent. Meanwhile, demands for metal resources are increasing while discovery rates to supply primary grade ores are not. This review re-thinks how bioaccumulation can be used and proposes that it can be developed for bioextractive applications-the removal and recovery of heavy metal ions for downstream purification and refining, rather than disposal. This review consolidates previously tested import-storage systems into a biochemical framework and highlights efforts to overcome obstacles that limit industrial feasibility, thereby identifying gaps in knowledge and potential avenues of research in bioaccumulation.
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Affiliation(s)
| | | | - Alexander F. Yakunin
- BioZone - Centre for Applied Biosciences and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
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14
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Abstract
Copper-binding metallophores, or chalkophores, play a role in microbial copper homeostasis that is analogous to that of siderophores in iron homeostasis. The best-studied chalkophores are members of the methanobactin (Mbn) family-ribosomally produced, posttranslationally modified natural products first identified as copper chelators responsible for copper uptake in methane-oxidizing bacteria. To date, Mbns have been characterized exclusively in those species, but there is genomic evidence for their production in a much wider range of bacteria. This review addresses the current state of knowledge regarding the function, biosynthesis, transport, and regulation of Mbns. While the roles of several proteins in these processes are supported by substantial genetic and biochemical evidence, key aspects of Mbn manufacture, handling, and regulation remain unclear. In addition, other natural products that have been proposed to mediate copper uptake as well as metallophores that have biologically relevant roles involving copper binding, but not copper uptake, are discussed.
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Affiliation(s)
- Grace E Kenney
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA; ,
| | - Amy C Rosenzweig
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA; ,
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
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15
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Progressive biogeochemical transformation of placer gold particles drives compositional changes in associated biofilm communities. FEMS Microbiol Ecol 2018; 94:4992300. [DOI: 10.1093/femsec/fiy080] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 05/01/2018] [Indexed: 11/14/2022] Open
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16
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Gomes TG, Hadi SIIA, Costa Alves GS, Mendonça S, De Siqueira FG, Miller RNG. Current Strategies for the Detoxification of Jatropha curcas Seed Cake: A Review. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:2510-2522. [PMID: 29498277 DOI: 10.1021/acs.jafc.7b05691] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Jatropha curcas is an important oilseed plant, with considerable potential in the development of biodiesel. Although Jatropha seed cake, the byproduct of oil extraction, is a residue rich in nitrogen, phosphorus, potassium, and carbon, with high protein content suitable for application in animal feed, the presence of toxic phorbol esters limits its application in feed supplements and fertilizers. This review summarizes the current methods available for detoxification of this residue, based upon chemical, physical, biological, or combined processes. The advantages and disadvantages of each process are discussed, and future directions involving genomic and proteomic approaches for advancing our understanding of biodegradation processes involving microorganisms are highlighted.
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Affiliation(s)
- Taisa G Gomes
- Instituto de Ciências Biológicas, Departamento de Biologia Celular , Universidade de Brasília , Campus Universitário Darcy Ribeiro, Asa Norte , 70910-900 , Brasília , DF , Brazil
| | - Sámed I I A Hadi
- Universidade Federal de Minas Gerais , Instituto de Ciências Biológicas - ICB , Av. Pres. Antônio Carlos, 6627 , 31270-010 , Belo Horizonte , MG , Brazil
| | - Gabriel S Costa Alves
- Instituto de Ciências Biológicas, Departamento de Biologia Celular , Universidade de Brasília , Campus Universitário Darcy Ribeiro, Asa Norte , 70910-900 , Brasília , DF , Brazil
| | - Simone Mendonça
- Embrapa Agroenergia, STN-70297-400 , 70297-400 , Brasília , DF , Brazil
| | | | - Robert N G Miller
- Instituto de Ciências Biológicas, Departamento de Biologia Celular , Universidade de Brasília , Campus Universitário Darcy Ribeiro, Asa Norte , 70910-900 , Brasília , DF , Brazil
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17
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Bütof L, Wiesemann N, Herzberg M, Altzschner M, Holleitner A, Reith F, Nies DH. Synergistic gold–copper detoxification at the core of gold biomineralisation inCupriavidus metallidurans. Metallomics 2018; 10:278-286. [DOI: 10.1039/c7mt00312a] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cupriavidus metalliduransescapes synergistic Cu/Au toxicity by re-oxidation of Au(i) back to Au(iii) using the periplasmic oxidase CopA.
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Affiliation(s)
- L. Bütof
- Molecular Microbiology, Institute for Biology/Microbiology
- Martin-Luther-University Halle-Wittenberg
- 06120 Halle (Saale)
- Germany
| | - N. Wiesemann
- Molecular Microbiology, Institute for Biology/Microbiology
- Martin-Luther-University Halle-Wittenberg
- 06120 Halle (Saale)
- Germany
| | - M. Herzberg
- Molecular Microbiology, Institute for Biology/Microbiology
- Martin-Luther-University Halle-Wittenberg
- 06120 Halle (Saale)
- Germany
| | - M. Altzschner
- Walter Schottky Institut and Physik-Department
- Technical University Munich
- Garching
- Germany
| | - A. Holleitner
- Walter Schottky Institut and Physik-Department
- Technical University Munich
- Garching
- Germany
| | - F. Reith
- The University of Adelaide
- School of Biological Sciences
- Adelaide
- Australia
| | - D. H. Nies
- Molecular Microbiology, Institute for Biology/Microbiology
- Martin-Luther-University Halle-Wittenberg
- 06120 Halle (Saale)
- Germany
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18
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Abstract
As the global population increases, so does the demand for minerals and energy resources. Demand for some of the major global commodities is currently growing at rates of: copper – 1.6% p.a.1; iron ore: 1.4% p.a.2; aluminium – 5% p.a.3; rare earth elements – 7% p.a.4, driven not only by population growth in China, India, and Africa, but also by increasing urbanisation and industrialisation globally. Technological advances in renewable energy production and storage, construction materials, transport, and computing could see demand for some of these resources spike by 2600% over the next 25 years under the most extreme demand scenarios5. Coupled with declining ore grades, this demand means that the global extent of mining environments is set to increase dramatically. Land disturbance attributed to mining was estimated to be 400 000 km2 in 20076, with projected rates of increase of 10 000 km2 per year7. This will increase the worldwide extent of mining environments from around 500 000 km2 at present to 1 330 000 km2 by 2100, larger than the combined land area of New South Wales and Victoria (1 050 000 km2), making them a globally important habitat for the hardiest of microbial life. The extreme geochemical and physical conditions prevalent in mining environments present great opportunities for discovery of novel microbial species and functions, as well as exciting challenges for microbiologists to apply their understanding to solve complex remediation problems.
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19
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Synergistic Toxicity of Copper and Gold Compounds in Cupriavidus metallidurans. Appl Environ Microbiol 2017; 83:AEM.01679-17. [PMID: 28939602 DOI: 10.1128/aem.01679-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/12/2017] [Indexed: 11/20/2022] Open
Abstract
The bacterium Cupriavidus metallidurans can reduce toxic gold(I/III) complexes and biomineralize them into metallic gold (Au) nanoparticles, thereby mediating the (trans)formation of Au nuggets. In Au-rich soils, most transition metals do not interfere with the resistance of this bacterium to toxic mobile Au complexes and can be removed from the cell by plasmid-encoded metal efflux systems. Copper is a noticeable exception: the presence of Au complexes and Cu ions results in synergistic toxicity, which is accompanied by an increased cytoplasmic Cu content and formation of Au nanoparticles in the periplasm. The periplasmic Cu-oxidase CopA was not essential for formation of the periplasmic Au nanoparticles. As shown with the purified and reconstituted Cu efflux system CupA, Au complexes block Cu-dependent release of phosphate from ATP by CupA, indicating inhibition of Cu transport. Moreover, Cu resistance of Au-inhibited cells was similar to that of mutants carrying deletions in the genes for the Cu-exporting PIB1-type ATPases. Consequently, Au complexes inhibit export of cytoplasmic Cu ions, leading to an increased cellular Cu content and decreased Cu and Au resistance. Uncovering the biochemical mechanisms of synergistic Au and Cu toxicity in C. metallidurans explains the issues this bacterium has to face in auriferous environments, where it is an important contributor to the environmental Au cycle.IMPORTANCE C. metallidurans lives in metal-rich environments, including auriferous soils that contain a mixture of toxic transition metal cations. We demonstrate here that copper ions and gold complexes exert synergistic toxicity because gold ions inhibit the copper-exporting P-type ATPase CupA, which is central to copper resistance in this bacterium. Such a situation should occur in soils overlying Au deposits, in which Cu/Au ratios usually are ≫1. Appreciating how C. metallidurans solves the problem of living in environments that contain both Au and Cu is a prerequisite to understand the molecular mechanisms underlying gold cycling in the environment, and the significance and opportunities of microbiota for specific targeting to Au in mineral exploration and ore processing.
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20
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Cerminati S, Giri GF, Mendoza JI, Soncini FC, Checa SK. The CpxR/CpxA system contributes to Salmonella gold-resistance by controlling the GolS-dependent gesABC transcription. Environ Microbiol 2017. [PMID: 28631419 DOI: 10.1111/1462-2920.13837] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several regulatory systems contribute to bacterial resistance to heavy metals controlling the expression of factors required to eliminate the intoxicant and/or to repair the damage caused by it. In Salmonella, the response to Au ions is mediated by the specific metalloregulator GolS that, among other genes, controls the expression of the RND-efflux pump GesABC. In this work, we demonstrate that CpxR/CpxA, a main cell-envelope stress-responding system, promotes gesABC transcription in the presence of Au ions at neutral pH. Deletion of either cpxA or cpxR, or mutation of the CpxR-binding site identified upstream of the GolS-operator in the gesABC promoter region reduces but does not abrogate the GolS- and Au-dependent activation of gesABC. Au also triggers the activation of the CpxR/CpxA system and deletion of the cpxRA operon severely reduces survival in the presence of the toxic metal. Our results indicate that the coordinated action of GolS and CpxR/CpxA contribute to protecting the cell from severe Au damage.
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Affiliation(s)
- Sebastián Cerminati
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Germán F Giri
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Julián I Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Fernando C Soncini
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
| | - Susana K Checa
- Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario (UNR), CONICET y Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR, Ocampo y Esmeralda, Rosario, Argentina
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