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Niu C, Zhao X, Shi D, Ying Y, Wu M, Lai CY, Guo J, Hu S, Liu T. Bioreduction of chromate in a syngas-based membrane biofilm reactor. JOURNAL OF HAZARDOUS MATERIALS 2024; 470:134195. [PMID: 38581872 DOI: 10.1016/j.jhazmat.2024.134195] [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: 01/02/2024] [Revised: 03/07/2024] [Accepted: 03/31/2024] [Indexed: 04/08/2024]
Abstract
This study leveraged synthesis gas (syngas), a renewable resource attainable through the gasification of biowaste, to achieve efficient chromate removal from water. To enhance syngas transfer efficiency, a membrane biofilm reactor (MBfR) was employed. Long-term reactor operation showed a stable and high-level chromate removal efficiency > 95%, yielding harmless Cr(III) precipitates, as visualised by scanning electron microscopy and energy dispersive X-ray analysis. Corresponding to the short hydraulic retention time of 0.25 days, a high chromate removal rate of 80 µmol/L/d was attained. In addition to chromate reduction, in situ production of volatile fatty acids (VFAs) by gas fermentation was observed. Three sets of in situ batch tests and two groups of ex situ batch tests jointly unravelled the mechanisms, showing that biological chromate reduction was primarily driven by VFAs produced from in situ syngas fermentation, whereas hydrogen originally present in the syngas played a minor role. 16 S rRNA gene amplicon sequencing has confirmed the enrichment of syngas-fermenting bacteria (such as Sporomusa), who performed in situ gas fermentation leading to the synthesis of VFAs, and organics-utilising bacteria (such as Aquitalea), who utilised VFAs to drive chromate reduction. These findings, combined with batch assays, elucidate the pathways orchestrating synergistic interactions between fermentative microbial cohorts and chromate-reducing microorganisms. The findings facilitate the development of cost-effective strategies for groundwater and drinking water remediation and present an alternative application scenario for syngas.
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Affiliation(s)
- Chenkai Niu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Xinyu Zhao
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Danting Shi
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, 999077, Hong Kong Special Administrative Region of China
| | - Yifeng Ying
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Mengxiong Wu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Chun-Yu Lai
- College of Environmental and Resource Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jianhua Guo
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Shihu Hu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Tao Liu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, 999077, Hong Kong Special Administrative Region of China.
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Wang GH, Tang CH, Cheng CY, Chung YC. Improving the practicality of recombinant Escherichia coli biosensor in detecting trace Cr(VI) by modifying the cryogenic storage conditions of biosensors and applying simple pretreatment. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2024; 58:1028-1038. [PMID: 38189371 DOI: 10.1080/10934529.2024.2301905] [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: 05/30/2023] [Accepted: 12/28/2023] [Indexed: 01/09/2024]
Abstract
Hexavalent chromium (Cr(VI)) is a global environmental pollutant. To reduce the risk caused by Cr(VI), a simple, accurate, reproducible, and inexpensive method for quantifying Cr(VI) in water and soil should be developed. In this study, three types of recombinant Escherichia coli biosensors (namely T7-lux-E. coli, T3-lux-E. coli, and SP6-lux-E. coli biosensor) containing promoters (T7, T3, and SP6), chromate-sensing regulator chrB, and the reporter gene luxAB were constructed. This study investigated the effects of cryogenic freezing temperature and time on trace Cr(VI) measurement by using recombinant E. coli biosensors. The results indicated that the activity of thawed frozen SP6-lux-E. coli cells stored at -20 °C for 270 days did not differ from that of freshly prepared cells. Turbidity and conductivity in water samples and organic matter in soil interfered with Cr(VI) measurement using the biosensor. The SP6-lux-E. coli biosensor exhibited a wide measurement range and a low deviation of <5% for measuring Cr(VI) in various Cr(VI)-contaminated water and soil samples and required only a simple pretreatment or extraction process even after 270-day storage at -20 °C. To the best of our knowledge, this is the first study to report the use of recombinant biosensors for accurately measuring Cr(VI) in both water and soil.
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Affiliation(s)
- Guey-Horng Wang
- Research Center of Natural Cosmeceuticals Engineering, Xiamen Medical College, Xiamen, China
| | - Chi-Hsiang Tang
- Department of Biological Science and Technology, China University of Science and Technology, Taipei, Taiwan
| | - Chiu-Yu Cheng
- Department of Biological Science and Technology, China University of Science and Technology, Taipei, Taiwan
| | - Ying-Chien Chung
- Department of Biological Science and Technology, China University of Science and Technology, Taipei, Taiwan
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Liu Y, Zhao X, Wang X, Ding A, Zhang D. Application of whole-cell bioreporters for ecological risk assessment and bioremediation potential evaluation after a benzene exceedance accident in groundwater in Lanzhou, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167846. [PMID: 37844638 DOI: 10.1016/j.scitotenv.2023.167846] [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: 07/14/2023] [Revised: 10/12/2023] [Accepted: 10/12/2023] [Indexed: 10/18/2023]
Abstract
Oil spill events challenge human health and ecosystem safety, which are priority concerned issues for sustainable development. There is then an increasing demand of tools for ecological risks assessment at contaminated sites. In this study, we introduced two whole-cell bioreporters, ADPWH_alk and ADPWH_recA, to measure the available n-alkanes and the genotoxicities of total petroleum hydrocarbons in soils and groundwater which were contaminated by the Benzene Exceedance Accident in Lanzhou, China. Comparing to traditional chemical analysis methods, the whole-cell bioreporter method could provide risk assessment on cell level within a shorter time and a less cost, which is economical and environment friendly. The highest contents of available alkanes in soil and groundwater were 18,737 mg/kg and 308.4 mg/L, respectively. In addition, the available n-alkanes significantly (p < 0.01) correlated to chemical analysis of total n-alkanes. The highest genotoxicity level was found in soil and groundwater samples with lower TPHs concentration (4338.0 mg/kg and 1.4 mg/L Mitomycin C equivalent), suggesting the significant impacts of geochemical variables and alkane availability on the ecological risks of petroleum contamination. Combining chemical analysis and whole-cell bioreporter results, bioremediation strategies were suggested for groundwater and soils with higher n-alkane availability and lower ecological risks, whereas chemical oxidation were suggested for other contaminated sites. For the first time, we mapped the distribution of available n-alkanes and petroleum toxicities in a large scale soil-groundwater system using whole-cell bioreporters, showing their huge potential for rapid contaminant detection and fast risk assessment.
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Affiliation(s)
- Yueqiao Liu
- Experiment and Practice Innovation Education Center, Beijing Normal University at Zhuhai, Zhuhai 519087, PR China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing Normal University, Beijing 100875, PR China
| | - Xiaohui Zhao
- China Institute of Water Resources and Hydropower Research, Beijing 100038, PR China
| | - Xinzi Wang
- School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Aizhong Ding
- College of Water Sciences, Beijing Normal University, Beijing 100875, PR China.
| | - Dayi Zhang
- College of New Energy and Environment, Jilin University, Changchun 130021, PR China; Key Laboratory of Groundwater Resources and Environment Ministry of Education, Jilin University, Changchun 130021, PR China.
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Huang CW, Lin C, Nguyen MK, Hussain A, Bui XT, Ngo HH. A review of biosensor for environmental monitoring: principle, application, and corresponding achievement of sustainable development goals. Bioengineered 2023; 14:58-80. [PMID: 37377408 DOI: 10.1080/21655979.2022.2095089] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 06/20/2022] [Accepted: 06/23/2022] [Indexed: 06/29/2023] Open
Abstract
Human health/socioeconomic development is closely correlated to environmental pollution, highlighting the need to monitor contaminants in the real environment with reliable devices such as biosensors. Recently, variety of biosensors gained high attention and employed as in-situ application, in real-time, and cost-effective analytical tools for healthy environment. For continuous environmental monitoring, it is necessary for portable, cost-effective, quick, and flexible biosensing devices. These benefits of the biosensor strategy are related to the Sustainable Development Goals (SDGs) established by the United Nations (UN), especially with reference to clean water and sources of energy. However, the relationship between SDGs and biosensor application for environmental monitoring is not well understood. In addition, some limitations and challenges might hinder the biosensor application on environmental monitoring. Herein, we reviewed the different types of biosensors, principle and applications, and their correlation with SDG 6, 12, 13, 14, and 15 as a reference for related authorities and administrators to consider. In this review, biosensors for different pollutants such as heavy metals and organics were documented. The present study highlights the application of biosensor for achieving SDGs. Current advantages and future research aspects are summarized in this paper.Abbreviations: ATP: Adenosine triphosphate; BOD: Biological oxygen demand; COD: Chemical oxygen demand; Cu-TCPP: Cu-porphyrin; DNA: Deoxyribonucleic acid; EDCs: Endocrine disrupting chemicals; EPA: U.S. Environmental Protection Agency; Fc-HPNs: Ferrocene (Fc)-based hollow polymeric nanospheres; Fe3O4@3D-GO: Fe3O4@three-dimensional graphene oxide; GC: Gas chromatography; GCE: Glassy carbon electrode; GFP: Green fluorescent protein; GHGs: Greenhouse gases; HPLC: High performance liquid chromatography; ICP-MS: Inductively coupled plasma mass spectrometry; ITO: Indium tin oxide; LAS: Linear alkylbenzene sulfonate; LIG: Laser-induced graphene; LOD: Limit of detection; ME: Magnetoelastic; MFC: Microbial fuel cell; MIP: Molecular imprinting polymers; MWCNT: Multi-walled carbon nanotube; MXC: Microbial electrochemical cell-based; NA: Nucleic acid; OBP: Odorant binding protein; OPs: Organophosphorus; PAHs: Polycyclic aromatic hydrocarbons; PBBs: Polybrominated biphenyls; PBDEs: Polybrominated diphenyl ethers; PCBs: Polychlorinated biphenyls; PGE: Polycrystalline gold electrode; photoMFC: photosynthetic MFC; POPs: Persistent organic pollutants; rGO: Reduced graphene oxide; RNA: Ribonucleic acid; SDGs: Sustainable Development Goals; SERS: Surface enhancement Raman spectrum; SPGE: Screen-printed gold electrode; SPR: Surface plasmon resonance; SWCNTs: single-walled carbon nanotubes; TCPP: Tetrakis (4-carboxyphenyl) porphyrin; TIRF: Total internal reflection fluorescence; TIRF: Total internal reflection fluorescence; TOL: Toluene-catabolic; TPHs: Total petroleum hydrocarbons; UN: United Nations; VOCs: Volatile organic compounds.
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Affiliation(s)
- Chi-Wei Huang
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Chitsan Lin
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
- Ph.D. Program in Maritime Science and Technology, College of Maritime, National Kaohsiung University of Science and TechnologyPh.D. Program in Maritime Science and Technology, Kaohsiung, Taiwan
| | - Minh Ky Nguyen
- Ph.D. Program in Maritime Science and Technology, College of Maritime, National Kaohsiung University of Science and TechnologyPh.D. Program in Maritime Science and Technology, Kaohsiung, Taiwan
| | - Adnan Hussain
- Ph. D. Program of Aquatic Science and Technology, College of Hydrosphere Science, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Xuan-Thanh Bui
- Department Water Science & Technology, Key Laboratory of Advanced Waste Treatment Technology, Ho Chi Minh City University of Technology (HCMUT), Vietnam National University Ho Chi Minh (VNU-HCM), Ho Chi Minh City, Vietnam
- Department Water Science & Technology, Faculty of Environment & Natural Resources, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam
| | - Huu Hao Ngo
- Department Water Science & Technology, Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney NSW, Australia
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Arik N, Elcin E, Tezcaner A, Oktem HA. Biosensing of arsenic by whole-cell bacterial bioreporter immobilized on polycaprolactone (PCL) electrospun fiber. ENVIRONMENTAL TECHNOLOGY 2023:1-13. [PMID: 37965791 DOI: 10.1080/09593330.2023.2283405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 09/19/2023] [Indexed: 11/16/2023]
Abstract
In recent years, heavy metals derived from several anthropogenic sources have both direct and indirect detrimental effects on the health of the environment and living organisms. Whole-cell bioreporters (WCBs) that can be used to monitor the levels of heavy metals in drinking and natural spring waters are important. In this study, whole-cell arsenic bacterial bioreporters were immobilized using polycaprolactone (PCL) electrospun fibers as the support material. The aim is to determine the properties of this immobilized bioreporter system by evaluating its performance in arsenic detection. Within the scope of the study, different growth media and fiber immobilization times were tested to determine the parameters affecting the fluorescent signals emitted by the immobilized bioreporter system in the presence of two dominant forms of arsenic, namely arsenite (As(III)) and arsenate (As(V)). In addition, the sensitivity, selectivity, response time, and shelf-life of the developed bioreporter system were evaluated. As far as the literature is concerned, this is the first study to investigate the potential of using PCL-electrospun fiber-immobilized fluorescent bacterial bioreporter for arsenic detection. This study will open new avenues in environmental arsenic monitoring.
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Affiliation(s)
- Nehir Arik
- Department of Molecular Biology and Genetics, Middle East Technical University, Ankara, Türkiye
| | - Evrim Elcin
- Department of Agricultural Biotechnology, Aydın Adnan Menderes University, Aydın, Türkiye
| | - Aysen Tezcaner
- Department of Engineering Sciences, Middle East Technical University, Ankara, Türkiye
- Center of Excellence in Biomaterials and Tissue Engineering (METU BIOMATEN), Ankara, Türkiye
| | - Huseyin A Oktem
- Department of Molecular Biology and Genetics, Middle East Technical University, Ankara, Türkiye
- Department of Biological Sciences, Middle East Technical University, Ankara, Türkiye
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Zhou X, Zhang X, Peng Y, Douka AI, You F, Yao J, Jiang X, Hu R, Yang H. Electroactive Microorganisms in Advanced Energy Technologies. Molecules 2023; 28:molecules28114372. [PMID: 37298848 DOI: 10.3390/molecules28114372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/22/2023] [Accepted: 05/22/2023] [Indexed: 06/12/2023] Open
Abstract
Large-scale production of green and pollution-free materials is crucial for deploying sustainable clean energy. Currently, the fabrication of traditional energy materials involves complex technological conditions and high costs, which significantly limits their broad application in the industry. Microorganisms involved in energy production have the advantages of inexpensive production and safe process and can minimize the problem of chemical reagents in environmental pollution. This paper reviews the mechanisms of electron transport, redox, metabolism, structure, and composition of electroactive microorganisms in synthesizing energy materials. It then discusses and summarizes the applications of microbial energy materials in electrocatalytic systems, sensors, and power generation devices. Lastly, the research progress and existing challenges for electroactive microorganisms in the energy and environment sectors described herein provide a theoretical basis for exploring the future application of electroactive microorganisms in energy materials.
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Affiliation(s)
- Xingchen Zhou
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, No. 206 Guanggu 1st Road, Wuhan 430205, China
| | - Xianzheng Zhang
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, No. 206 Guanggu 1st Road, Wuhan 430205, China
| | - Yujie Peng
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, No. 206 Guanggu 1st Road, Wuhan 430205, China
| | - Abdoulkader Ibro Douka
- State Key Laboratory of Fine Chemicals, Zhang Dayu School of Chemistry, Dalian University of Technology, Dalian 116024, China
| | - Feng You
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, No. 206 Guanggu 1st Road, Wuhan 430205, China
| | - Junlong Yao
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, No. 206 Guanggu 1st Road, Wuhan 430205, China
| | - Xueliang Jiang
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, No. 206 Guanggu 1st Road, Wuhan 430205, China
| | - Ruofei Hu
- Department of Food Science and Chemical Engineering, Hubei University of Arts and Science, Xiangyang 441053, China
| | - Huan Yang
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, No. 206 Guanggu 1st Road, Wuhan 430205, China
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Vezeau GE, Gadila LR, Salis HM. Automated design of protein-binding riboswitches for sensing human biomarkers in a cell-free expression system. Nat Commun 2023; 14:2416. [PMID: 37105971 PMCID: PMC10140043 DOI: 10.1038/s41467-023-38098-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Cell-free genetically encoded biosensors have been developed to detect small molecules and nucleic acids, but they have yet to be reliably engineered to detect proteins. Here we develop an automated platform to convert protein-binding RNA aptamers into riboswitch sensors that operate within low-cost cell-free assays. We demonstrate the platform by engineering 35 protein-sensing riboswitches for human monomeric C-reactive protein, human interleukin-32γ, and phage MS2 coat protein. The riboswitch sensors regulate output expression levels by up to 16-fold with input protein concentrations within the human serum range. We identify two distinct mechanisms governing riboswitch-mediated regulation of translation rates and leverage computational analysis to refine the protein-binding aptamer regions, improving design accuracy. Overall, we expand the cell-free sensor toolbox and demonstrate how computational design is used to develop protein-sensing riboswitches with future applications as low-cost medical diagnostics.
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Affiliation(s)
- Grace E Vezeau
- Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Lipika R Gadila
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Howard M Salis
- Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Huck Institute Bioinformatics and Genomics Graduate Program, Pennsylvania State University, University Park, PA, 16802, USA.
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Delatour E, Pagnout C, Zaffino ML, Duval JFL. Comparative Analysis of Cell Metabolic Activity Sensing by Escherichia coli rrnB P1-lux and Cd Responsive-Lux Biosensors: Time-Resolved Experiments and Mechanistic Modelling. BIOSENSORS 2022; 12:763. [PMID: 36140148 PMCID: PMC9496673 DOI: 10.3390/bios12090763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/09/2022] [Accepted: 09/11/2022] [Indexed: 06/16/2023]
Abstract
Whole-cell bacterial sensors are used in medical/environmental applications to detect chemicals, and to assess medium toxicity or stress. Non-specific constitutive biosensors generally serve the latter purpose, whereas chemical detection is performed with biosensors involving a specific chemical-inducible promoter. Herein, we show that functioning principles of specific and non-specific whole-cell biosensors are not exclusive as both can probe modulations of cell metabolic activity under stressing conditions. The demonstration is based on (i) time-resolved measurements of bioluminescence produced by constitutive rrnB P1-luxCDABE Escherichia coli biosensor in media differing with respect to carbon source, (ii) theoretical reconstruction of the measured signals using a here-reported theory for bioluminescence generated by constitutive cells, (iii) comparison between time-dependent cell photoactivity (reflecting metabolic activity) retrieved by theory with that we reported recently for cadmium-inducible PzntA-luxCDABE E. coli in media of similar compositions. Whereas signals of constitutive and non-constitutive biosensors differ in terms of shape, amplitude and peak number depending on nutritional medium conditions, analysis highlights the features shared by their respective cell photoactivity patterns mediated by the interplay between stringent response and catabolite repressions. The work advocates for the benefits of a theoretical interpretation for the time-dependent response of biosensors to unravel metabolic and physicochemical contributions to the bioluminescence signal.
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Affiliation(s)
- Eva Delatour
- Université de Lorraine, CNRS, LIEC (Laboratoire Interdisciplinaire des Environnements Continentaux), UMR7360, Campus Bridoux, F-57070 Metz, France
| | - Christophe Pagnout
- Université de Lorraine, CNRS, LIEC (Laboratoire Interdisciplinaire des Environnements Continentaux), UMR7360, Campus Bridoux, F-57070 Metz, France
| | - Marie L. Zaffino
- Université de Lorraine, CNRS, LIEC (Laboratoire Interdisciplinaire des Environnements Continentaux), UMR7360, Campus Bridoux, F-57070 Metz, France
| | - Jérôme F. L. Duval
- Université de Lorraine, CNRS, LIEC, UMR7360, F-54501 Vandoeuvre-lès-Nancy, France
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Wang GH, Cheng CY, Tsai TH, Chiang PK, Chung YC. Highly Sensitive Luminescent Bioassay Using Recombinant Escherichia coli Biosensor for Rapid Detection of Low Cr(VI) Concentration in Environmental Water. BIOSENSORS-BASEL 2021; 11:bios11100357. [PMID: 34677313 PMCID: PMC8534196 DOI: 10.3390/bios11100357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 01/24/2023]
Abstract
In this study, we constructed a recombinant Escherichia coli strain with different promoters inserted between the chromate-sensing regulator chrB and the reporter gene luxAB to sense low hexavalent chromium (Cr(VI)) concentrations (<0.05 mg/L); subsequently, its biosensor characteristics (sensitivity, selectivity, and specificity) for measuring Cr(VI) in various water bodies were evaluated. The luminescence intensity of each biosensor depended on pH, temperature, detection time, coexisting carbon source, coexisting ion, Cr(VI) oxyanion form, Cr(VI) concentration, cell type, and type of medium. Recombinant lux-expressing E. coli with the T7 promoter (T7-lux-E. coli, limit of detection (LOD) = 0.0005 mg/L) had the highest luminescence intensity or was the most sensitive for Cr(VI) detection, followed by E. coli with the T3 promoter (T3-lux-E. coli, LOD = 0.001 mg/L) and that with the SP6 promoter (SP6-lux-E. coli, LOD = 0.005 mg/L). All biosensors could be used to determine whether the Cr(VI) standard was met in terms of water quality, even when using thawing frozen cells as biosensors after 90-day cryogenic storage. The SP6-lux-E. coli biosensor had the shortest detection time (0.5 h) and the highest adaptability to environmental interference. The T7-lux-E. coli biosensor—with the optimal LOD, a wide measurement range (0.0005–0.5 mg/L), and low deviation (−5.0–7.9%) in detecting Cr(VI) from industrial effluents, domestic effluents, and surface water—is an efficient Cr(VI) biosensor. This unprecedented study is to evaluate recombinant lux E. coli with dissimilar promoters for their possible practice in Cr(VI) measurement in water bodies, and the biosensor performance is clearly superior to that of past systems in terms of detection time, LOD, and detection deviation for real water samples.
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Affiliation(s)
- Guey-Horng Wang
- Research Center of Natural Cosmeceuticals Engineering, Xiamen Medical College, Xiamen 361008, China;
| | - Chiu-Yu Cheng
- Department of Biological Science and Technology, China University of Science and Technology, Taipei 115, Taiwan; (C.-Y.C.); (P.-K.C.)
| | - Teh-Hua Tsai
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei 10608, Taiwan;
| | - Pin-Kuan Chiang
- Department of Biological Science and Technology, China University of Science and Technology, Taipei 115, Taiwan; (C.-Y.C.); (P.-K.C.)
| | - Ying-Chien Chung
- Department of Biological Science and Technology, China University of Science and Technology, Taipei 115, Taiwan; (C.-Y.C.); (P.-K.C.)
- Correspondence: ; Tel.: +886-22782-1862; Fax: +886-22786-5456
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Ali SA, Mittal D, Kaur G. In-situ monitoring of xenobiotics using genetically engineered whole-cell-based microbial biosensors: recent advances and outlook. World J Microbiol Biotechnol 2021; 37:81. [PMID: 33843020 DOI: 10.1007/s11274-021-03024-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 02/25/2021] [Indexed: 02/07/2023]
Abstract
Industrialisation, directly or indirectly, exposes humans to various xenobiotics. The increased magnitude of chemical pesticides and toxic heavy metals in the environment, as well as their intrusion into the food chain, seriously threatens human health. Therefore, the surveillance of xenobiotics is crucial for social safety and security. Online investigation by traditional methods is not sufficient for the detection and identification of such compounds because of the high costs and their complexity. Advancement in the field of genetic engineering provides a potential opportunity to use genetically modified microorganisms. In this regard, whole-cell-based microbial biosensors (WCBMB) represent an essential tool that couples genetically engineered organisms with an operator/promoter derived from a heavy metal-resistant operon combined with a regulatory protein in the gene circuit. The plasmid controls the expression of the reporter gene, such as gfp, luc, lux and lacZ, to an inducible gene promoter and has been widely applied to assay toxicity and bioavailability. This review summarises the recent trends in the development and application of microbial biosensors and the use of mobile genes for biomedical and environmental safety concerns.
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Affiliation(s)
- Syed Azmal Ali
- Proteomics and Cell Biology Lab, Animal Biotechnology Center, National Dairy Research Institute, Karnal, Haryana, India. .,Proteomics and Cell Biology Lab, Animal Biotechnology Center, ICAR-National Dairy Research Institute, 132001, Karnal, Haryana, India.
| | - Deepti Mittal
- Animal Biochemistry Division, National Dairy Research Institute, Karnal, Haryana, India
| | - Gurjeet Kaur
- Centre for Healthy Brain Ageing, School of Psychiatry, University of New South Wales, 2052, Sydney, NSW, Australia
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Del Valle I, Fulk EM, Kalvapalle P, Silberg JJ, Masiello CA, Stadler LB. Translating New Synthetic Biology Advances for Biosensing Into the Earth and Environmental Sciences. Front Microbiol 2021; 11:618373. [PMID: 33633695 PMCID: PMC7901896 DOI: 10.3389/fmicb.2020.618373] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/17/2020] [Indexed: 12/26/2022] Open
Abstract
The rapid diversification of synthetic biology tools holds promise in making some classically hard-to-solve environmental problems tractable. Here we review longstanding problems in the Earth and environmental sciences that could be addressed using engineered microbes as micron-scale sensors (biosensors). Biosensors can offer new perspectives on open questions, including understanding microbial behaviors in heterogeneous matrices like soils, sediments, and wastewater systems, tracking cryptic element cycling in the Earth system, and establishing the dynamics of microbe-microbe, microbe-plant, and microbe-material interactions. Before these new tools can reach their potential, however, a suite of biological parts and microbial chassis appropriate for environmental conditions must be developed by the synthetic biology community. This includes diversifying sensing modules to obtain information relevant to environmental questions, creating output signals that allow dynamic reporting from hard-to-image environmental materials, and tuning these sensors so that they reliably function long enough to be useful for environmental studies. Finally, ethical questions related to the use of synthetic biosensors in environmental applications are discussed.
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Affiliation(s)
- Ilenne Del Valle
- Systems, Synthetic, and Physical Biology Graduate Program, Rice University, Houston, TX, United States
| | - Emily M. Fulk
- Systems, Synthetic, and Physical Biology Graduate Program, Rice University, Houston, TX, United States
| | - Prashant Kalvapalle
- Systems, Synthetic, and Physical Biology Graduate Program, Rice University, Houston, TX, United States
| | - Jonathan J. Silberg
- Department of BioSciences, Rice University, Houston, TX, United States
- Department of Bioengineering, Rice University, Houston, TX, United States
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX, United States
| | - Caroline A. Masiello
- Department of BioSciences, Rice University, Houston, TX, United States
- Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, United States
- Department of Chemistry, Rice University, Houston, TX, United States
| | - Lauren B. Stadler
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, United States
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12
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Luo JH, Wu M, Liu J, Qian G, Yuan Z, Guo J. Microbial chromate reduction coupled with anaerobic oxidation of methane in a membrane biofilm reactor. ENVIRONMENT INTERNATIONAL 2019; 130:104926. [PMID: 31228790 DOI: 10.1016/j.envint.2019.104926] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/02/2019] [Accepted: 06/12/2019] [Indexed: 06/09/2023]
Abstract
It has been reported that microbial reduction of sulfate, nitrite/nitrate and iron/manganese could be coupled with anaerobic oxidation of methane (AOM), which plays a significant role in controlling methane emission from anoxic niches. However, little is known about microbial chromate (Cr(VI)) reduction coupling with AOM. In this study, a microbial consortium was enriched via switching nitrate dosing to chromate feeding as the sole electron acceptor under anaerobic condition in a membrane biofilm reactor (MBfR), in which methane was continuously provided as the electron donor through bubble-less hollow fiber membranes. According to long-term reactor operation and chromium speciation analysis, soluble chromate could be reduced into Cr(III) compounds by using methane as electron donor. Fluorescence in situ hybridization and high-throughput 16S rRNA gene amplicon profiling further indicated that after feeding chromate Candidatus 'Methanoperedens' (a known nitrate-dependent anaerobic methane oxidation archaeon) became sole anaerobic methanotroph in the biofilm, potentially responsible for the chromate bio-reduction driven by methane. Two potential pathways of the microbial AOM-coupled chromate reduction were proposed: (i) Candidatus 'Methanoperedens' independently utilizes chromate as electron acceptor to form Cr(III) compounds, or (ii) Candidatus 'Methanoperedens' oxidizes methane to generate intermediates or electrons, which will be utilized to reduce chromate to Cr(III) compounds by unknown chromate reducers synergistically. Our findings suggest a possible link between the biogeochemical chromium and methane cycles.
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Affiliation(s)
- Jing-Huan Luo
- Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland 4072, Australia; School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China
| | - Mengxiong Wu
- Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Jianyong Liu
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China
| | - Guangren Qian
- School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China
| | - Zhiguo Yuan
- Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland 4072, Australia.
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13
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Two plant-hosted whole-cell bacterial biosensors for detection of bioavailable Cr(VI). World J Microbiol Biotechnol 2019; 35:129. [DOI: 10.1007/s11274-019-2703-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 07/26/2019] [Indexed: 10/26/2022]
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14
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Tamindžija D, Chromikova Z, Spaić A, Barak I, Bernier-Latmani R, Radnović D. Chromate tolerance and removal of bacterial strains isolated from uncontaminated and chromium-polluted environments. World J Microbiol Biotechnol 2019; 35:56. [PMID: 30900044 DOI: 10.1007/s11274-019-2638-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 03/14/2019] [Indexed: 10/27/2022]
Abstract
Investigation of bacterial chromate tolerance has mostly focused on strains originating from polluted sites. In the present study, we isolated 33 chromate tolerant strains from diverse environments harbouring varying concentrations of chromium (Cr). All of these strains were able to grow on minimal media with at least 2 mM hexavalent chromium (Cr(VI)) and their classification revealed that they belonged to 12 different species and 8 genera, with a majority (n = 20) being affiliated to the Bacillus cereus group. Selected B. cereus group strains were further characterised for their chromate tolerance level and the ability to remove toxic Cr(VI) from solution. A similar level of chromate tolerance was observed in isolates originating from environments harbouring high or low Cr. Reference B. cereus strains exhibited the same Cr(VI) tolerance which indicates that a high chromate tolerance could be an intrinsic group characteristic. Cr(VI) removal varied from 22.9% (strain PCr2a) to 98.5% (strain NCr4). Strains NCr1a and PCr12 exhibited the ability to grow to the greatest extent in Cr(VI) containing media (maximum growth of 65.3% and 64.9% relative to that in the absence of Cr(VI), respectively) accompanied with high chromate removal activity (73.7% and 74.4%, respectively), making them prime candidates for the investigation of chromate tolerance mechanisms in Gram-positive bacteria and Cr(VI) bioremediation applications.
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Affiliation(s)
- Dragana Tamindžija
- Faculty of Sciences, Department of Chemistry, Biochemistry and Environmental Protection, University of Novi Sad, Trg Dositeja Obradovića 3, Novi Sad, 21000, Serbia
| | - Zuzana Chromikova
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, Bratislava, 845 51, Slovakia
| | - Andrea Spaić
- Faculty of Sciences, Department of Biology and Ecology, University of Novi Sad, Trg Dositeja Obradovića 2, Novi Sad, 21000, Serbia
| | - Imrich Barak
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, Bratislava, 845 51, Slovakia
| | - Rizlan Bernier-Latmani
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - Dragan Radnović
- Faculty of Sciences, Department of Biology and Ecology, University of Novi Sad, Trg Dositeja Obradovića 2, Novi Sad, 21000, Serbia.
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15
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Khatun MA, Hoque MA, Zhang Y, Lu T, Cui L, Zhou NY, Feng Y. Bacterial Consortium-Based Sensing System for Detecting Organophosphorus Pesticides. Anal Chem 2018; 90:10577-10584. [DOI: 10.1021/acs.analchem.8b02709] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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16
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Modulating the sensing properties of Escherichia coli-based bioreporters for cadmium and mercury. Appl Microbiol Biotechnol 2018; 102:4863-4872. [DOI: 10.1007/s00253-018-8960-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 03/20/2018] [Accepted: 03/21/2018] [Indexed: 10/17/2022]
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17
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Impact of plant-associated bacteria biosensors on plant growth in the presence of hexavalent chromium. World J Microbiol Biotechnol 2017; 34:12. [DOI: 10.1007/s11274-017-2389-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 12/01/2017] [Indexed: 12/18/2022]
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18
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Synthetic biology for microbial heavy metal biosensors. Anal Bioanal Chem 2017; 410:1191-1203. [DOI: 10.1007/s00216-017-0751-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 10/23/2017] [Accepted: 11/07/2017] [Indexed: 11/26/2022]
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19
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A Green Microbial Fuel Cell-Based Biosensor for In Situ Chromium (VI) Measurement in Electroplating Wastewater. SENSORS 2017; 17:s17112461. [PMID: 29076985 PMCID: PMC5712896 DOI: 10.3390/s17112461] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 10/20/2017] [Accepted: 10/24/2017] [Indexed: 11/25/2022]
Abstract
The extensive use of Cr(VI) in many industries and the disposal of Cr(VI)-containing wastes have resulted in Cr(VI)-induced environmental contamination. Cr(VI) compounds are associated with increased cancer risks; hence, the detection of toxic Cr(VI) compounds is crucial. Various methods have been developed for Cr(VI) measurement, but they are often conducted offsite and cannot provide real-time toxicity monitoring. A microbial fuel cell (MFC) is an eco-friendly and self-sustaining device that has great potential as a biosensor for in situ Cr(VI) measurement, especially for wastewater generated from different electroplating units. In this study, Exiguobacterium aestuarii YC211, a facultatively anaerobic, Cr(VI)-reducing, salt-tolerant, and exoelectrogenic bacterium, was isolated and inoculated into an MFC to evaluate its feasibility as a Cr(VI) biosensor. The Cr(VI) removal efficiency of E. aestuarii YC211 was not affected by the surrounding environment (pH 5–9, 20–35 °C, coexisting ions, and salinity of 0–15 g/L). The maximum power density of the MFC biosensor was 98.3 ± 1.5 mW/m2 at 1500 Ω. A good linear relationship (r2 = 0.997) was observed between the Cr(VI) concentration (2.5–60 mg/L) and the voltage output. The developed MFC biosensor is a simple device that can accurately measure Cr(VI) concentrations in the actual electroplating wastewater that is generated from different electroplating units within 30 min with low deviations (−6.1% to 2.2%). After treating the actual electroplating wastewater with the MFC, the predominant family in the biofilm was found to be Bacillaceae (95.3%) and was further identified as the originally inoculated E. aestuarii YC211 by next generation sequencing (NGS). Thus, the MFC biosensor can measure Cr(VI) concentrations in situ in the effluents from different electroplating units, and it can potentially help in preventing the violation of effluent regulations.
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20
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Gui Q, Lawson T, Shan S, Yan L, Liu Y. The Application of Whole Cell-Based Biosensors for Use in Environmental Analysis and in Medical Diagnostics. SENSORS 2017; 17:s17071623. [PMID: 28703749 PMCID: PMC5539819 DOI: 10.3390/s17071623] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 07/07/2017] [Accepted: 07/08/2017] [Indexed: 01/11/2023]
Abstract
Various whole cell-based biosensors have been reported in the literature for the last 20 years and these reports have shown great potential for their use in the areas of pollution detection in environmental and in biomedical diagnostics. Unlike other reviews of this growing field, this mini-review argues that: (1) the selection of reporter genes and their regulatory proteins are directly linked to the performance of celllular biosensors; (2) broad enhancements in microelectronics and information technologies have also led to improvements in the performance of these sensors; (3) their future potential is most apparent in their use in the areas of medical diagnostics and in environmental monitoring; and (4) currently the most promising work is focused on the better integration of cellular sensors with nano and micro scaled integrated chips. With better integration it may become practical to see these cells used as (5) real-time portable devices for diagnostics at the bedside and for remote environmental toxin detection and this in situ application will make the technology commonplace and thus as unremarkable as other ubiquitous technologies.
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Affiliation(s)
- Qingyuan Gui
- Laboratory of Nanoscale Biosensing and Bioimaging, Instiute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xueyuanxi Road, Wenzhou 325027, China.
| | - Tom Lawson
- ARC Center of Excellence for Nanoscale BioPhotonics, Macquarie University, Sydney, NSW 2109, Australia.
| | - Suyan Shan
- Laboratory of Nanoscale Biosensing and Bioimaging, Instiute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xueyuanxi Road, Wenzhou 325027, China.
| | - Lu Yan
- Laboratory of Nanoscale Biosensing and Bioimaging, Instiute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xueyuanxi Road, Wenzhou 325027, China.
| | - Yong Liu
- Laboratory of Nanoscale Biosensing and Bioimaging, Instiute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xueyuanxi Road, Wenzhou 325027, China.
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21
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Bereza-Malcolm L, Aracic S, Franks AE. Development and Application of a Synthetically-Derived Lead Biosensor Construct for Use in Gram-Negative Bacteria. SENSORS (BASEL, SWITZERLAND) 2016; 16:E2174. [PMID: 27999352 PMCID: PMC5191153 DOI: 10.3390/s16122174] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/09/2016] [Accepted: 12/13/2016] [Indexed: 02/05/2023]
Abstract
The use of lead in manufacturing has decreased significantly over the last few decades. However, previous widespread use of lead-containing products and their incorrect disposal has resulted in environmental contamination. Accumulation of harmful quantities of lead pose a threat to all living organisms, through inhalation, ingestion, or direct contact, resulting in lead poisoning. This study utilized synthetic biology principles to develop plasmid-based whole-cell bacterial biosensors for detection of lead. The genetic element of the lead biosensor construct consists of pbrR, which encodes the regulatory protein, together with its divergent promoter region and a promoterless gfp. GFP expression is controlled by PbrR in response to the presence of lead. The lead biosensor genetic element was cloned onto a low-copy number broad host range plasmid, which can stably exist in a range of laboratory and environmental isolates, including Pseudomonas, Shewanella, and Enterobacter. The biosensors constructed were found to be sensitive, rapid, and specific and could, as such, serve as monitoring tools for lead-contaminated water.
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Affiliation(s)
- Lara Bereza-Malcolm
- Applied and Environmental Microbiology Laboratory, Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria 3086, Australia.
| | - Sanja Aracic
- Applied and Environmental Microbiology Laboratory, Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria 3086, Australia.
| | - Ashley E Franks
- Applied and Environmental Microbiology Laboratory, Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria 3086, Australia.
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22
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Utility of Ochrobactrum anthropi YC152 in a Microbial Fuel Cell as an Early Warning Device for Hexavalent Chromium Determination. SENSORS 2016; 16:s16081272. [PMID: 27537887 PMCID: PMC5017437 DOI: 10.3390/s16081272] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 07/15/2016] [Accepted: 08/08/2016] [Indexed: 11/17/2022]
Abstract
Fast hexavalent chromium (Cr(VI)) determination is important for environmental risk and health-related considerations. We used a microbial fuel cell-based biosensor inoculated with a facultatively anaerobic, Cr(VI)-reducing, and exoelectrogenic Ochrobactrum anthropi YC152 to determine the Cr(VI) concentration in water. The results indicated that O. anthropi YC152 exhibited high adaptability to pH, temperature, salinity, and water quality under anaerobic conditions. The stable performance of the microbial fuel cell (MFC)-based biosensor indicated its potential as a reliable biosensor system. The MFC voltage decreased as the Cr(VI) concentration in the MFC increased. Two satisfactory linear relationships were observed between the Cr(VI) concentration and voltage output for various Cr(VI) concentration ranges (0.0125-0.3 mg/L and 0.3-5 mg/L). The MFC biosensor is a simple device that can accurately measure Cr(VI) concentrations in drinking water, groundwater, and electroplating wastewater in 45 min with low deviations (<10%). The use of the biosensor can help in preventing the violation of effluent regulations and the maximum allowable concentration of Cr(VI) in water. Thus, the developed MFC biosensor has potential as an early warning detection device for Cr(VI) determination even if O. anthropi YC152 is a possible opportunistic pathogen.
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23
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Yoon Y, Kim S, Chae Y, Kang Y, Lee Y, Jeong SW, An YJ. Use of Tunable Whole-Cell Bioreporters to Assess Bioavailable Cadmium and Remediation Performance in Soils. PLoS One 2016; 11:e0154506. [PMID: 27171374 PMCID: PMC4865175 DOI: 10.1371/journal.pone.0154506] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 04/14/2016] [Indexed: 11/18/2022] Open
Abstract
It is important to have tools to measure the bioavailability to assess the risks of pollutants because the bioavailability is defined as the portions of pollutants showing the biological effects on living organisms. This study described the construction of tunable Escherichia coli whole-cell bioreporter (WCB) using the promoter region of zinc-inducible operon and its application on contaminated soils. It was verified that this WCB system showed specific and sensitive responses to cadmium rather than zinc in the experimental conditions. It was inferred that Cd(II) associates stronger with ZntR, a regulatory protein of zinc-inducible operon, than other metal ions. Moreover, the expression of reporter genes, egfp and mcherry, were proportional to the concentration of cadmium, thereby being a quantitative sensor to monitor bioavailable cadmium. The capability to determine bioavailable cadmium was verified with Cd(II) amended LUFA soils, and then the applicability on environmental systems was investigated with field soils collected from smelter area in Korea before and after soil-washing. The total amount of cadmium was decreased after soil washing, while the bioavailability was increased. Consequently, it would be valuable to have tools to assess bioavailability and the effectiveness of soil remediation should be evaluated in the aspect of bioavailability as well as removal efficiency.
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Affiliation(s)
- Youngdae Yoon
- Department of Environmental Health Science, Konkuk University, Seoul 05029, Korea
| | - Sunghoon Kim
- Department of Environmental Health Science, Konkuk University, Seoul 05029, Korea
| | - Yooeun Chae
- Department of Environmental Health Science, Konkuk University, Seoul 05029, Korea
| | - Yerin Kang
- Department of Environmental Health Science, Konkuk University, Seoul 05029, Korea
| | - Youngshim Lee
- Division of Bioscience and Biotechnology, BMIC, Konkuk University, Seoul 05029, Korea
| | - Seung-Woo Jeong
- Department of Environmental Engineering, Kunsan National University, Kunsan 54150, Korea
| | - Youn-Joo An
- Department of Environmental Health Science, Konkuk University, Seoul 05029, Korea
- * E-mail:
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24
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Yoon Y, Kim S, Chae Y, Kim SW, Kang Y, An G, Jeong SW, An YJ. Simultaneous detection of bioavailable arsenic and cadmium in contaminated soils using dual-sensing bioreporters. Appl Microbiol Biotechnol 2016; 100:3713-22. [PMID: 26852408 DOI: 10.1007/s00253-016-7338-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 01/13/2016] [Accepted: 01/15/2016] [Indexed: 11/29/2022]
Abstract
Whole-cell bioreporters (WCBs) have attracted increasing attention during the last few decades because they allow fast determination of bioavailable heavy metals in contaminated sites. Various WCBs to monitor specific heavy metals such as arsenic and cadmium in diverse environmental systems are available. However, currently, no study on simultaneous analysis of arsenic and cadmium has been reported, even though soils are contaminated by diverse heavy metals and metalloids. We demonstrated herein the development of dual-sensing WCBs to simultaneously quantify bioavailable arsenic and cadmium in contaminated sites by employing the promoter regions of the ars and znt operons as separate metal-sensing domains, and egfp and mcherry as reporter genes. The dual-sensing WCBs were generated by inserting two sets of genes into E. coli DH5α. The capability of WCBs was successfully proved to simultaneously quantify bioavailable arsenic and cadmium in amended Landwirtschaftliche Untersuchungs und Forschungsanstalt (LUFA) soils, and then, it was applied to contaminated field soils collected from a smelter area in Korea. As a result, it was noticed that the bioavailable portion of cadmium was higher than that of arsenic while the absolute amount of bioavailable arsenic and cadmium level was opposite. Since both cadmium and arsenic were assessed from the same E. coli cells, the data obtained by using dual-sensing WCBs would be more efficient and convenient than that from comparative WCB assay. In spite of advantageous aspects, to our knowledge, this is the first report on a dual-sensing WCB for rapid and concurrent quantification of bioavailable arsenic and cadmium in contaminated soils.
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Affiliation(s)
- Youngdae Yoon
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, South Korea
| | - Sunghoon Kim
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, South Korea
| | - Yooeun Chae
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, South Korea
| | - Shin Woong Kim
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, South Korea
| | - Yerin Kang
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, South Korea
| | - Gyeonghyeon An
- Department of Environmental Engineering, Kunsan National University, Kunsan, 54150, South Korea
| | - Seung-Woo Jeong
- Department of Environmental Engineering, Kunsan National University, Kunsan, 54150, South Korea
| | - Youn-Joo An
- Department of Environmental Health Science, Konkuk University, Seoul, 05029, South Korea.
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25
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Yoon Y, Kang Y, Chae Y, Kim S, Lee Y, Jeong SW, An YJ. Arsenic bioavailability in soils before and after soil washing: the use of Escherichia coli whole-cell bioreporters. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:2353-2361. [PMID: 26411448 DOI: 10.1007/s11356-015-5457-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 09/17/2015] [Indexed: 06/05/2023]
Abstract
We investigated the quantification of bioavailable arsenic in contaminated soils and evaluation of soil-washing processes in the aspect of bioavailability using a novel bacterial bioreporter developed in present study. The whole-cell bioreporter (WCB) was genetically engineered by fusing the promoter of nik operon from Escherichia coli and green fluorescent protein as a sensing domain and reporter domain. Among eight well-known hazardous heavy metals and metalloid, this system responded specifically to arsenic, thereby inferring association of As(III) with NikR inhibits the repression. Moreover, the response was proportional to the concentration of As(III), thereby it was capable to determine the amount of bioavailable arsenic quantitatively in contaminated soils. The bioavailable portion of arsenic was 5.9 (3.46-10.96) and 0.9 (0.27-1.74) % of total from amended and site soils, respectively, suggesting the bioavailability of arsenic in soils was related to the soil properties and duration of aging. On the other hand, only 1.37 (0.21-2.97) % of total arsenic was extracted into soil solutions and 19.88 (11.86-28.27) % of arsenic in soil solution was bioavailable. This result showed that the soluble arsenic is not all bioavailable and most of bioavailable arsenic in soils is water non-extractable. In addition, the bioavailable arsenic was increased after soil-washing while total amount was decreased, thereby suggesting the soil-washing processes release arsenic associated with soil materials to be bioavailable. Therefore, it would be valuable to have a tool to assess bioavailability and the bioavailability should be taken into consideration for soil remediation plans.
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Affiliation(s)
- Youngdae Yoon
- Department of Environmental Science, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea
| | - Yerin Kang
- Department of Environmental Science, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea
| | - Yooeun Chae
- Department of Environmental Science, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea
| | - Sunghoon Kim
- Department of Environmental Science, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea
| | - Youngshim Lee
- Division of Bioscience and Biotechnology, BMIC, Konkuk University, Seoul, 143-701, Korea
| | - Seung-Woo Jeong
- Department of Environmental Engineering, Kunsan National University, Kunsan, 573-701, Korea
| | - Youn-Joo An
- Department of Environmental Science, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, 143-701, Korea.
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Durand MJ, Hua A, Jouanneau S, Cregut M, Thouand G. Detection of Metal and Organometallic Compounds with Bioluminescent Bacterial Bioassays. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2015:77-99. [PMID: 26475470 DOI: 10.1007/10_2015_332] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Chemical detection of metal and organometallic compounds is very specific and sensitive, but these techniques are time consuming and expensive. Although these techniques provide information about the concentrations of compounds, they fail to inform us about the toxicity of a sample. Because the toxic effects of metals and organometallic compounds are influenced by a multitude of environmental factors, such as pH, the presence of chelating agents, speciation, and organic matter, bioassays have been developed for ecotoxicological studies. Among these bioassays, recombinant luminescent bacteria have been developed over the past 20 years, and many of them are specific for the detection of metals and metalloids. These bioassays are simple to use, are inexpensive, and provide information on the bioavailable fraction of metals and organometals. Thus, they are an essential complementary tool for providing information beyond chemical analysis. In this chapter, we propose to investigate the detection of metals and organometallic compounds with bioluminescent bacterial bioassays and the applications of these bioassays to environmental samples. Graphical Abstract.
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Affiliation(s)
- M J Durand
- University of Nantes, UMR CNRS GEPEA 6144, 18 Bd Gaston Defferre, 85000, La Roche sur Yon, France.
| | - A Hua
- University of Nantes, UMR CNRS GEPEA 6144, 18 Bd Gaston Defferre, 85000, La Roche sur Yon, France
| | - S Jouanneau
- University of Nantes, UMR CNRS GEPEA 6144, 18 Bd Gaston Defferre, 85000, La Roche sur Yon, France
| | - M Cregut
- Capacités SAS, 26 Bd Vincent Gâche, 44200, Nantes, France
| | - G Thouand
- University of Nantes, UMR CNRS GEPEA 6144, 18 Bd Gaston Defferre, 85000, La Roche sur Yon, France
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27
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Coelho C, Branco R, Natal-da-Luz T, Sousa JP, Morais PV. Evaluation of bacterial biosensors to determine chromate bioavailability and to assess ecotoxicity of soils. CHEMOSPHERE 2015; 128:62-69. [PMID: 25655820 DOI: 10.1016/j.chemosphere.2014.12.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 11/07/2014] [Accepted: 12/08/2014] [Indexed: 06/04/2023]
Abstract
Chromate can be considered a potent environmental contaminant and consequently, an understanding of chromate availability and toxicity to soil biology is essential for effective ecological assessment of metal impact in soils. This study shows the response of two bacterial bioreporters, pCHRGFP1 Escherichiacoli and pCHRGFP2 Ochrobactrumtritici, to increasing concentrations of chromate in two different soils. The bioreporters, carrying the regulatory gene chrB transcriptionally fused to the gfp reporter system, exhibited different features. In both, the fluorescence signal and the chromate concentration could be linearly correlated but E. coli biosensor functioned within the range of 0.5-2 μM and O. tritici biosensor within 2-10 μM chromate. The bioreporters were validated through comparative measurements using the chemical chromate methods of diphenylcarbazide and ionic chromatography. The bacterial sensors were used for the estimation of bioavailable fraction of chromate in a natural soil and OECD artificial soil, both spiked with chromate in increasing concentrations of 0-120 mg Cr(VI) kg(-1) of soil. OECD soil showed a faster chromate decrease comparing to the natural soil. The toxicity of soils amended with chromate was also evaluated by ecotoxicological tests through collembolan reproduction tests using Folsomia candida as test organism. Significant correlations were found between collembolans reproduction and chromate concentration in soil (lower at high chromate concentrations) measured by biosensors. Data obtained showed that the biosensors tested are sensitive to chromate presence in soil and may constitute a rapid and efficient method to measure chromate availability in soils.
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Affiliation(s)
| | | | | | - José Paulo Sousa
- IMAR-CMA, 3004-517 Coimbra, Portugal; Department of Life Sciences, FCTUC, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Paula V Morais
- IMAR-CMA, 3004-517 Coimbra, Portugal; Department of Life Sciences, FCTUC, University of Coimbra, 3001-401 Coimbra, Portugal.
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28
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Bereza-Malcolm LT, Mann G, Franks AE. Environmental sensing of heavy metals through whole cell microbial biosensors: a synthetic biology approach. ACS Synth Biol 2015; 4:535-46. [PMID: 25299321 DOI: 10.1021/sb500286r] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Whole cell microbial biosensors are offering an alternative means for rapid, on-site heavy metal detection. Based in microorganisms, biosensing constructs are designed and constructed to produce both qualitative and quantitative outputs in response to heavy metal ions. Previous microbial biosensors designs are focused on single-input constructs; however, development of multiplexed systems is resulting in more flexible designs. The movement of microbial biosensors from laboratory based designs toward on-site, functioning heavy metal detectors has been hindered by the toxic nature of heavy metals, along with the lack of specificity of heavy metals promoter elements. Applying a synthetic biology approach with alternative microbial chassis may increase the robustness of microbial biosensors and mitigate these issues. Before full applications are achieved, further consideration has to be made regarding the risk and regulations of whole cell microbial biosensor use in the environment. To this end, a standard framework for future whole cell microbial biosensor design and use is proposed.
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Affiliation(s)
| | - Gülay Mann
- Defence Science
and Technology Organisation, Fishermans Bend,
Port Melbourne, 3207 Victoria, Australia
| | - Ashley Edwin Franks
- Department
of Microbiology, La Trobe University, Bundoora, 3086 Victoria, Australia
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29
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Adeniran A, Sherer M, Tyo KE. Yeast-based biosensors: design and applications. FEMS Yeast Res 2014; 15:1-15. [DOI: 10.1111/1567-1364.12203] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 05/19/2014] [Accepted: 08/19/2014] [Indexed: 12/30/2022] Open
Affiliation(s)
- Adebola Adeniran
- Department of Chemical & Biological Engineering; Northwestern University; Evanston IL USA
| | - Michael Sherer
- Department of Chemical & Biological Engineering; Northwestern University; Evanston IL USA
| | - Keith E.J. Tyo
- Department of Chemical & Biological Engineering; Northwestern University; Evanston IL USA
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30
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Reimer A, Yagur-Kroll S, Belkin S, Roy S, van der Meer JR. Escherichia [corrected] coli ribose binding protein based bioreporters revisited. Sci Rep 2014; 4:5626. [PMID: 25005019 PMCID: PMC4088097 DOI: 10.1038/srep05626] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 06/17/2014] [Indexed: 01/09/2023] Open
Abstract
Bioreporter bacteria, i.e., strains engineered to respond to chemical exposure by production of reporter proteins, have attracted wide interest because of their potential to offer cheap and simple alternative analytics for specified compounds or conditions. Bioreporter construction has mostly exploited the natural variation of sensory proteins, but it has been proposed that computational design of new substrate binding properties could lead to completely novel detection specificities at very low affinities. Here we reconstruct a bioreporter system based on the native Escherichia coli ribose binding protein RbsB and one of its computationally designed variants, reported to be capable of binding 2,4,6-trinitrotoluene (TNT). Our results show in vivo reporter induction at 50 nM ribose, and a 125 nM affinity constant for in vitro ribose binding to RbsB. In contrast, the purified published TNT-binding variant did not bind TNT nor did TNT cause induction of the E. coli reporter system.
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Affiliation(s)
- Artur Reimer
- Department of Fundamental Microbiology, University of Lausanne, Bâtiment Biophore, Quartier UNIL-Sorge 1015 Lausanne, Switzerland
| | - Sharon Yagur-Kroll
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Shimshon Belkin
- Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Shantanu Roy
- Department of Fundamental Microbiology, University of Lausanne, Bâtiment Biophore, Quartier UNIL-Sorge 1015 Lausanne, Switzerland
| | - Jan Roelof van der Meer
- Department of Fundamental Microbiology, University of Lausanne, Bâtiment Biophore, Quartier UNIL-Sorge 1015 Lausanne, Switzerland
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31
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Tantimongcolwat T, Isarankura-Na-Ayudhya C, Srisarin A, Galla HJ, Prachayasittikul V. Polyacrylamide hydrogel encapsulated E. coli expressing metal-sensing green fluorescent protein as a potential tool for copper ion determination. EXCLI JOURNAL 2014; 13:401-15. [PMID: 26417267 PMCID: PMC4464391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 03/27/2014] [Indexed: 11/29/2022]
Abstract
A simple, inexpensive and field applicable metal determination system would be a powerful tool for the efficient control of metal ion contamination in various sources e.g. drinking-water, water reservoir and waste discharges. In this study, we developed a cell-based metal sensor for specific and real-time detection of copper ions. E. coli expressing metal-sensing green fluorescent protein (designated as TG1/(CG)6GFP and TG1/H6CdBP4GFP) were constructed and served as a metal analytical system. Copper ions were found to exert a fluorescence quenching effect, while zinc and cadmium ions caused minor fluorescence enhancement in the engineered bacterial suspension. To construct a user-friendly and reagentless metal detection system, TG1/H6CdBP4GFP and TG1/(CG)6GFP were encapsulated in polyacrylamide hydrogels that were subsequently immobilized on an optical fiber equipped with a fluorescence detection module. The sensor could be applied to measure metal ions by simply dipping the encapsulated bacteria into a metal solution and monitoring fluorescence changes in real time as a function of the metal concentration in solution. The sensor system demonstrated high specificity toward copper ions. The fluorescence intensities of the encapsulated TG1/(CG)6GFP and TG1/H6CdBP4GFP were quenched by approximately 70 % and 80 % by a high-dose of copper ions (50 mM), respectively. The level of fluorescence quenching exhibited a direct correlation with the copper concentration, with a linear correlation coefficient (r) of 0.99. The cell-based metal sensor was able to efficiently monitor copper concentrations ranging between 5 M and 50 mM, encompassing the maximum allowed copper contamination in drinking water (31.15 M) established by the WHO. Furthermore, the cell-based metal sensor could undergo prolonged storage for at least 2 weeks without significantly influencing the copper sensitivity.
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Affiliation(s)
- Tanawut Tantimongcolwat
- Center for Innovation Development and Technology Transfer, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand
| | | | - Apapan Srisarin
- Department of Clinical Microscopy, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand
| | - Hans-Joachim Galla
- Institute of Biochemistry, University of Muenster, Wilhelm-Klemm-Str. 2, Muenster 48149, Germany
| | - Virapong Prachayasittikul
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand,*To whom correspondence should be addressed: Virapong Prachayasittikul, Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand; phone: +6624414376; Fax: +6624414380, E-mail:
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32
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Branco R, Morais PV. Identification and characterization of the transcriptional regulator ChrB in the chromate resistance determinant of Ochrobactrum tritici 5bvl1. PLoS One 2013; 8:e77987. [PMID: 24223748 PMCID: PMC3817168 DOI: 10.1371/journal.pone.0077987] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 09/06/2013] [Indexed: 12/30/2022] Open
Abstract
Ochrobactrum tritici 5bvl1 is able to resist to high concentrations of chromate through the expression of an inducible chromate-resistant determinant, found in a mobile element (TnOtChr), which carries the genes, chrB, chrA, chrC and chrF. The regulation of chr operon present in TnOtChr, which is controlled by a transcriptional regulator, ChrB, was characterized in the current work. Fusions of chr promoter, or chr promoter and chrB gene, upstream of a gfp reporter gene, identified the most probable promoter sequence within the tnpR-chrB intergenic region. This region contains an AT-rich imperfect inverted repeat sequence, which overlaps a part of the −10 sequence. The results of the in vitro DNA-binding assays with purified ChrB (His- or no-tagged) showed that the protein binds directly to the chr promoter region. In order to identify the ChrB functional domain for sensing chromate stress and for DNA-binding, site-directed mutagenesis of ChrB was performed. Among several single amino acid mutants, three mutants (R180; R187 and H229) prevented chromate induction without any modification to the protein’s stability. Interestingly, two ChrB mutants (R18 and R23) were constitutively active, regardless of chromate stress conditions, indicating that the residues most probably belong to the protein-DNA binding site. As such, the ChrB was classified as a transcriptional regulator that recognizes a specific DNA sequence, regulating the expression of a chromate resistance determinant.
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Affiliation(s)
- Rita Branco
- IMAR-CMA-Marine and Environmental Research Centre, Coimbra, Portugal
- Interdisciplinary Research Institute, University of Coimbra, Coimbra, Portugal
| | - Paula V. Morais
- IMAR-CMA-Marine and Environmental Research Centre, Coimbra, Portugal
- Department of Life Sciences, FCTUC, University of Coimbra, Coimbra, Portugal
- * E-mail:
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