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Cai Y, Zhu K, Shen L, Ma J, Bao L, Chen D, Wei L, Wei N, Liu B, Wu Y, Chen S. Evolved Biosensor with High Sensitivity and Specificity for Measuring Cadmium in Actual Environmental Samples. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:10062-10071. [PMID: 35762704 DOI: 10.1021/acs.est.2c00627] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Bacterial biosensors have great potential in contaminant detection for sensitivity, specificity, cost-effectiveness, and easy operation. However, the existing cadmium-responsive bacterial biosensors cannot meet the real-world detection requirements due to lack of sensitivity, specificity, and anti-interference capability. This study aimed to develop a bacterial biosensor for detecting the total and extractable cadmium in actual environmental samples. We constructed the cadmium-responsive biosensor with the regulatory element (cadmium resistance transcriptional regulatory, CadR) and the reporting element (GFP) and improved its performance by directed evolution. The mutant libraries of biosensors were generated by error-prone PCR and screened by continuous five-round fluorescence-activated cell sorting (FACS), and a bacteria variant epCadR5 with higher performance was finally isolated. Biosensor fluorescence intensity was measured by a microplate reader, and results showed that the evolved cadmium-responsive bacterial biosensor was of high sensitivity and specificity in detecting trace cadmium, with a detection limit of 0.45 μg/L, which is 6.8 times more specific to cadmium than that of the wild-type. Furthermore, microscopic qualitative analysis results showed that the bacteria could produce fluorescence response in a cadmium-contaminated soil matrix, and quantitative analysis results showed that the values of cadmium from epCadR5 bacteria were close to that from inductively coupled plasma-mass spectrometry. These results suggest that the biosensor may have a broad application prospect in the detection of cadmium-contaminated soil and water.
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Affiliation(s)
- Yeshen Cai
- Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- University of Science and Technology of China, Hefei 230026, China
| | - Kaili Zhu
- Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- University of Science and Technology of China, Hefei 230026, China
| | - Liang Shen
- Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- University of Science and Technology of China, Hefei 230026, China
| | - Jie Ma
- School of Public Health, Wannan Medical College, Wuhu 241002, China
| | - Lingzhi Bao
- School of Public Health, Wannan Medical College, Wuhu 241002, China
| | - Dongdong Chen
- Institute of Environmental Physics and Technology, Anhui University, Hefei 230039, China
| | - Liangchen Wei
- School of Public Health, Wannan Medical College, Wuhu 241002, China
| | - Nan Wei
- Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- University of Science and Technology of China, Hefei 230026, China
| | - Binmei Liu
- Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- University of Science and Technology of China, Hefei 230026, China
| | - Yuejin Wu
- Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- University of Science and Technology of China, Hefei 230026, China
| | - Shaopeng Chen
- Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- University of Science and Technology of China, Hefei 230026, China
- School of Public Health, Wannan Medical College, Wuhu 241002, China
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Prabhakaran R, Rajkumar SN, Ramprasath T, Selvam GS. Identification of promoter P cadR, in silico characterization of cadmium resistant gene cadR and molecular cloning of promoter P cadR from Pseudomonas aeruginosa BC15. Toxicol Ind Health 2018; 34:819-833. [PMID: 30407121 DOI: 10.1177/0748233718795934] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cadmium (Cd) remediation in Pseudomonas aeruginosa is achieved through the function of two vital genes, cadA and cadR, that code for P-type ATPase (CadA) and transcription regulatory protein (CadR), respectively. Although numerous studies are available on these metal-sensing and regulatory proteins, the promoter of these genes, metal sensing and binding ability, are poorly understood. The present work is aimed at the characterization of the CadR protein, identification of the PcadR promoter and protein-promoter-metal binding affinity using bioinformatics and to validate the results by cloning the PcadR promoter in Escherichia coli DH5α. The promoter regions and its curvature were identified and analysed using PePPER software (University of Groningen, The Netherland) and the Bendit program (Version: v.1.0), respectively. Using Phyre, the three-dimensional structure of CadR was modelled, and the structure was validated by Ramachandran plots. The DNA-binding domain was present in the N-terminal region of CadR. A dimeric interface was observed in helix-turn-helix and metal ion-binding sites at the C-terminal. Docking studies showed higher affinity of Cd to both CadR (Atomic contact energy = -15.04 kcal/Mol) and PcadR (Atomic contact energy = -40.18 kcal/Mol) when compared to other metal ions. CadR with PcadR showed the highest binding affinity (Atomic contact energy= -250.40 kcal/Mol) when compared with PcadA. In vitro studies using green fluorescent protein tagged with PcadR (gfp-PcadR) cloned in E. coli-expressed gfp protein in a concentration-dependent manner upon Cd exposure. Based on our in silico studies and in vitro molecular cloning analysis, we conclude that PcadR and CadR are active only in the presence of Cd. The CadR protein has the highest binding affinity with PcadR. As it became apparent that the cadR gene regulates the PcadR activity in the presence of Cd with high specificity, and the cadR and PcadR can be used as a biological tool for development of a microbial biosensor.
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Affiliation(s)
- Rajkumar Prabhakaran
- Department of Biochemistry, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
| | | | - Tharmarajan Ramprasath
- Center for Molecular and Translational Medicine, Petit Science Center, Georgia State University, Atlanta, GA, USA
| | - Govindan Sadasivam Selvam
- Department of Biochemistry, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
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Zhang M, Huang F, Wang G, Liu X, Wen J, Zhang X, Huang Y, Xia Y. Geographic distribution of cadmium and its interaction with the microbial community in the Longjiang River: risk evaluation after a shocking pollution accident. Sci Rep 2017; 7:227. [PMID: 28331217 PMCID: PMC5427973 DOI: 10.1038/s41598-017-00280-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/17/2017] [Indexed: 12/14/2022] Open
Abstract
A shocking Longjiang River cadmium pollution accident occurred in 2012, the effects of which on microbial communities remain unclear. Alkaline precipitation technology was applied for remediation, but concerns rose about the stability of this technology. To understand the geographic distribution of cadmium and its correlation with microbes, in this study, 39 water samples and 39 sludge samples from this river and 2 soil samples from the nearby farmland were collected for chemical and microbial analyses. The Cd concentrations of all water samples were lower than 0.005 mg/L and reached the quality standards for Chinese surface water. A ranking of sludge samples based on Cd contents showed sewage outfall > dosing sites > farmland, all of which were higher than the quality standard for soil. Alkaline precipitation technology was effective for Cd precipitation. Cd was unstable; it was constantly dissolving and being released from the sludge. The Cd content of each phase was mainly influenced by the total Cd content. Over 40,000 effective sequences were detected in each sample, and a total of 59,833 OTUs and 1,273 genera were found using Illumina MiSeq sequencing. Two phyla and 39 genera were notably positively correlated with the Cd distribution, while the cases of 10 phyla and 6 genera were the opposite.
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Affiliation(s)
- MingJiang Zhang
- National Engineering Laboratory of Biohydrometallurgy, General Research Institute for Nonferrous Metals, No. 2 Xinjiekouwai Street, Beijing, 100088, China
| | - FuKe Huang
- Institute of HeChi Scientific-Technical Information, No. 385 West Ring Road of HeChi City, GuangXi Zhuang Autonomous Region, 547000, China
| | - GuangYuan Wang
- National Engineering Laboratory of Biohydrometallurgy, General Research Institute for Nonferrous Metals, No. 2 Xinjiekouwai Street, Beijing, 100088, China
| | - XingYu Liu
- National Engineering Laboratory of Biohydrometallurgy, General Research Institute for Nonferrous Metals, No. 2 Xinjiekouwai Street, Beijing, 100088, China.
| | - JianKang Wen
- National Engineering Laboratory of Biohydrometallurgy, General Research Institute for Nonferrous Metals, No. 2 Xinjiekouwai Street, Beijing, 100088, China
| | - XiaoSheng Zhang
- Institute of HeChi Scientific-Technical Information, No. 385 West Ring Road of HeChi City, GuangXi Zhuang Autonomous Region, 547000, China
| | - YaoSi Huang
- Institute of HeChi Scientific-Technical Information, No. 385 West Ring Road of HeChi City, GuangXi Zhuang Autonomous Region, 547000, China
| | - Yu Xia
- National Engineering Laboratory of Biohydrometallurgy, General Research Institute for Nonferrous Metals, No. 2 Xinjiekouwai Street, Beijing, 100088, China
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Li J, Wei X, Yu P, Deng X, Xu W, Ma M, Zhang H. Expression of cadR Enhances its Specific Activity for Cd Detoxification and Accumulation in Arabidopsis. PLANT & CELL PHYSIOLOGY 2016; 57:1720-1731. [PMID: 27382127 DOI: 10.1093/pcp/pcw093] [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: 10/01/2015] [Accepted: 05/02/2016] [Indexed: 06/06/2023]
Abstract
Cadmium (Cd) is a transition metal that is highly toxic in biological systems. Anthropogenic emissions of Cd have increased biogeochemical cycling and the amount of Cd in the biosphere. Here we studied the utility of a bacterial Cd-binding protein, CadR, for the remediation of Cd contamination. CadR was successfully targeted to chloroplasts using a constitutive Cauliflower mosaic virus (CaMV) 35S promoter or a shoot-specific Chl a/b-binding protein 2 gene (CAB2) promoter and an RbcS (small subunit of the Rubisco complex) transit peptide. Under short-term (2 d) exposure to Cd, the cadR transgenic plants showed up to a 2.9-fold Cd accumulation in roots compared with untransformed plants. Under medium term (7 d) exposure to Cd, the concentrations of Cd in leaves began to increase but there were no differences between the wild type and the cadR transgenic plants. Under long-term (16 d) exposure to Cd, the cadR transgenic plants accumulated greater amounts of Cd in leaves than the untransformed plants. Total Cd accumulation (µg per plant) in shoots and roots of the plants expressing cadR were significantly higher (up to 3.5-fold in shoots and 5.2-fold in roots) than those of the untransformed plants. We also found that targeting CadR to chloroplasts facilitated chloroplastic metal homeostasis and Chl b accumulation. Our results demonstrate that manipulating chelating capacity in chloroplasts or in the cytoplasm may be effective in modifying both the accumulation of and resistance to Cd.
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Affiliation(s)
- Jingrui Li
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China College of Life Science, Shanxi Normal University, Shanxi Linfen 041004, China These authors contributed equally to this work
| | - Xuezhi Wei
- College of Life Science, Shanxi Normal University, Shanxi Linfen 041004, China These authors contributed equally to this work
| | - Pengli Yu
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Xin Deng
- Department of Chemistry and Institute for Biophysical Dynamics, the University of Chicago, Chicago, IL 60637, USA
| | - Wenxiu Xu
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Mi Ma
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Haiyan Zhang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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