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Du R, Guo M, He X, Huang K, Luo Y, Xu W. Feedback regulation mode of gene circuits directly affects the detection range and sensitivity of lead and mercury microbial biosensors. Anal Chim Acta 2019; 1084:85-92. [PMID: 31519238 DOI: 10.1016/j.aca.2019.08.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 07/19/2019] [Accepted: 08/04/2019] [Indexed: 02/05/2023]
Abstract
Whole cell biosensors offer high potential for the detection of heavy metals in a manner that is simple, rapid and low-cost. However, previous researchers have paid little attention to the impacts of construction models on the performance of these biosensors, thereby limiting the achievement of rational design and the optimization of detection characteristics. Herein, for the first time, three basic models of lead and mercury detection circuits, namely feedback coupled, uncoupled and semi-coupled models, have been constructed and compared to explore the effects of uncoupling the topology of sensing circuits on the reporter signals. The results demonstrated that the uncoupled model had better sensitivity for both lead (50 nM) and mercury (1 nM), while the feedback coupled circuits had a wider detection range for mercury (10 nM - 7.5 μM). Introducing the semi-coupled model into the comparison revealed that both the type and location of promoters for regulatory protein genes were key factors for sensitivity. Moreover, the detection characteristics of the uncoupled biosensors were robust, as conditions such as induction time, the concentration of microbial cells, and the concentration of antibiotics had little interference on the performance of the microbial biosensors. This study also established a novel and simple pre-treatment method for sample detection by biosensors. When the uncoupled microbial biosensor was put into practice, the concentration levels of mercury in milk and lead in sewage were determined quickly and accurately. Our study, therefore, provides a strategy for the rational design of whole cell heavy metal biosensors and has developed the potential of their application.
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Affiliation(s)
- Ruoxi Du
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100194, PR China; Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety), Ministry of Agriculture, Beijing, 100083, PR China
| | - Mingzhang Guo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100194, PR China; Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety), Ministry of Agriculture, Beijing, 100083, PR China
| | - Xiaoyun He
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100194, PR China; Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety), Ministry of Agriculture, Beijing, 100083, PR China
| | - Kunlun Huang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100194, PR China; Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety), Ministry of Agriculture, Beijing, 100083, PR China
| | - Yunbo Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100194, PR China; Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety), Ministry of Agriculture, Beijing, 100083, PR China
| | - Wentao Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100194, PR China; Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety), Ministry of Agriculture, Beijing, 100083, PR China.
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152
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Kepel B, Ekawati Tallei T. Potential of Organic Mercury-resistant Bacteria Isolated from Mercury Contaminated Sites for Organic Mercury Remediation. Pak J Biol Sci 2019; 22:45-50. [PMID: 30796768 DOI: 10.3923/pjbs.2019.45.50] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND AND OBJECTIVE Efforts at organic mercury detoxification can be carried out using resistant bacteria that can live in an environment contaminated with the compound. This study aimed at isolating and identifying resistant bacteria from mercury-contaminated environments and analysing their ability to detoxify organic mercury. MATERIALS AND METHODS Soil samples were obtained from 3 gold processing locations that make use of mercury in Tanoyan Village, Bolaang Mongondow district, North Sulawesi province. The identification was carried out on the mercury-resistant bacteria through morphological and molecular tests. Bacteria which were highly resistant to mercury were examined for their ability to detoxify phenyl mercury (organic mercury). RESULTS The study showed that 8 mercury-resistant bacterial colonies could be isolated from the three soil samples. The bacteria were able to grow in LB broth containing 10 mg L-1 of phenyl mercury. Four isolates (AA, BB, CC and DD) were even able to grow in 40 mg L-1 of phenyl mercury. According to the identification tests, those bacteria were Pseudomonas sp. (AA, DD), Pseudomonas aeruginosa (BB) and Proteus mirabilis (CC). Testing of organic mercury against isolates of bacteria which are highly resistant to it in order to determine their detoxification capacity revealed that all four isolates could reduce levels of the compound in media, based on the results, starting from the highest was Pseudomonas sp. 74.99%, then Pseudomonas aeruginosa 60.23% and Proteus mirabilis 47.59% after 24 h of incubation. CONCLUSION The study suggested that there are four bacteria that have potentials to remediate organic mercury contamination sites.
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153
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Christensen GA, Gionfriddo CM, King AJ, Moberly JG, Miller CL, Somenahally AC, Callister SJ, Brewer H, Podar M, Brown SD, Palumbo AV, Brandt CC, Wymore AM, Brooks SC, Hwang C, Fields MW, Wall JD, Gilmour CC, Elias DA. Determining the Reliability of Measuring Mercury Cycling Gene Abundance with Correlations with Mercury and Methylmercury Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:8649-8663. [PMID: 31260289 DOI: 10.1021/acs.est.8b06389] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Methylmercury (MeHg) is a bioaccumulative toxic contaminant in many ecosystems, but factors governing its production are poorly understood. Recent work has shown that the anaerobic microbial conversion of mercury (Hg) to MeHg requires the Hg-methylation genes hgcAB and that these genes can be used as biomarkers in PCR-based estimators of Hg-methylator abundance. In an effort to determine reliable methods for assessing hgcA abundance and diversity and linking them to MeHg concentrations, multiple approaches were compared including metagenomic shotgun sequencing, 16S rRNA gene pyrosequencing and cloning/sequencing hgcAB gene products. Hg-methylator abundance was also determined by quantitative hgcA qPCR amplification and metaproteomics for comparison to the above measurements. Samples from eight sites were examined covering a range of total Hg (HgT; 0.03-14 mg kg-1 dry wt. soil) and MeHg (0.05-27 μg kg-1 dry wt. soil) concentrations. In the metagenome and amplicon sequencing of hgcAB diversity, the Deltaproteobacteria were the dominant Hg-methylators while Firmicutes and methanogenic Archaea were typically ∼50% less abundant. This was consistent with metaproteomics estimates where the Deltaproteobacteria were steadily higher. The 16S rRNA gene pyrosequencing did not have sufficient resolution to identify hgcAB+ species. Metagenomic and hgcAB results were similar for Hg-methylator diversity and clade-specific qPCR-based approaches for hgcA are only appropriate when comparing the abundance of a particular clade across various samples. Weak correlations between Hg-methylating bacteria and soil Hg concentrations were observed for similar environmental samples, but overall total Hg and MeHg concentrations poorly correlated with Hg-cycling genes.
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Affiliation(s)
- Geoff A Christensen
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Caitlin M Gionfriddo
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Andrew J King
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - James G Moberly
- College of Engineering , University of Idaho , Moscow , Idaho 83844 , United States
| | - Carrie L Miller
- School of Theoretical and Applied Science , Ramapo College of New Jersey , Mahwah , New Jersey 07430 , United States
| | - Anil C Somenahally
- Department of Soil and Crop Sciences , Texas A&M University , Overton , Texas 77843-2474 , United States
| | - Stephen J Callister
- Biological Sciences Division , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Heather Brewer
- Biological Sciences Division , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Mircea Podar
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Steven D Brown
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Anthony V Palumbo
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Craig C Brandt
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Ann M Wymore
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
| | - Scott C Brooks
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37830 , United States
| | - Chiachi Hwang
- Center for Biofilm Engineering , Montana State University , Bozeman , Montana 59717 , United States
| | - Matthew W Fields
- Department of Microbiology and Immunology , Montana State University , Bozeman , Montana 59717 , United States
- Center for Biofilm Engineering , Montana State University , Bozeman , Montana 59717 , United States
| | - Judy D Wall
- Department of Biochemistry , University of Missouri , Columbia , Missouri 65211 , United States
| | - Cynthia C Gilmour
- Smithsonian Environmental Research Center , Edgewater , Maryland 21037 , United States
| | - Dwayne A Elias
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831-6342 , United States
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154
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Azaroff A, Tessier E, Deborde J, Guyoneaud R, Monperrus M. Mercury and methylmercury concentrations, sources and distribution in submarine canyon sediments (Capbreton, SW France): Implications for the net methylmercury production. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 673:511-521. [PMID: 30995585 DOI: 10.1016/j.scitotenv.2019.04.111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 04/08/2019] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
Submarine canyons are important stocks of commercial interest fish, whose consumption is one of the main monomethymercury (MeHg) exposure to humans. Currently, biogeochemistry of mercury in those biologically productive system is unknown. In this work, inorganic mercury (Hg(II)) and organic mercury (MeHg) distributions were measured in sedimentary accumulative zones (slopes and terraces) against adjacent continental shelf sediments. Hg compound concentrations in these sediments show a huge range of concentrations (Hg(II) ranging from 18 to 973 ng g-1 and MeHg ranging from 0.07 to 2.03 ng g-1) exhibiting factors 50 and 20 fold, respectively. Higher values of mercury compounds were observed in canyon locations suggesting a high accumulation of mercury associated with higher values of clay fraction and organic matter content. The reactivity of mercury was investigated in sediment of three locations along Capbreton submarine canyon axis using slurry incubations experiments and isotopic tracers. Specific methylation and demethylation rate constants (kM and kD) were calculated. Results clearly showed that MeHg concentrations in these sediments are controlled by competing and simultaneous methylation and demethylation reactions mainly mediated by biotic process. Mercury reactivity was found higher in coastal stations compared to the offshore station due to more labile organic matter which may stimulate microbial activities. However, higher net MeHg production was estimated for the offshore station due to high Hg(II) concentrations suggesting a potential MeHg source for such marine environments.
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Affiliation(s)
- Alyssa Azaroff
- CNRS/ UNIV PAU & PAYS ADOUR/ E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux - MIRA, UMR 5254, 64600 Anglet, France
| | - Emmanuel Tessier
- CNRS/ UNIV PAU & PAYS ADOUR/ E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux - MIRA, UMR 5254, 64000 Pau, France
| | - Jonathan Deborde
- CNRS/ UNIV PAU & PAYS ADOUR/ E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux - MIRA, UMR 5254, 64600 Anglet, France
| | - Rémy Guyoneaud
- CNRS/ UNIV PAU & PAYS ADOUR/ E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux - MIRA, UMR 5254, 64000 Pau, France
| | - Mathilde Monperrus
- CNRS/ UNIV PAU & PAYS ADOUR/ E2S UPPA, Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux - MIRA, UMR 5254, 64600 Anglet, France.
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155
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Beckers F, Mothes S, Abrigata J, Zhao J, Gao Y, Rinklebe J. Mobilization of mercury species under dynamic laboratory redox conditions in a contaminated floodplain soil as affected by biochar and sugar beet factory lime. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 672:604-617. [PMID: 30970288 DOI: 10.1016/j.scitotenv.2019.03.401] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/21/2019] [Accepted: 03/25/2019] [Indexed: 06/09/2023]
Abstract
Mercury and its species are toxic and therefore strategies to immobilize them or to impede the formation of bioaccumulative MeHg are a hot topic of ongoing research. Biochar (BC) and sugar beet factory lime (SBFL) are suggested to have the potential to meet these goals. However, their ability to restrain the mobilization of total Hg (Hgt), methylmercury (MeHg), and ethylmercury (EtHg) or the formation of MeHg and EtHg has not been examined to date. Moreover, the effect of systematically altered redox conditions on the release dynamics of Hgt, MeHg, and EtHg in a contaminated floodplain soil as affected by these soil amendments has not been studied. Therefore, we investigated the impact of pre-defined redox conditions on the release dynamics of Hgt, MeHg, and EtHg in a contaminated floodplain soil (CS) and the soil amended with either BC (CS+BC) or SBFL (CS+SBFL). The mobilization of Hgt, MeHg, and EtHg was generally higher at low redox potential (EH) and decreased with increasing EH, irrespective of soil treatment. Both BC and SBFL diminished the release of Hgt from soil but not the methylation and ethylation of Hg. In CS+SBFL approximately half of Hgt was found in solution compared to CS. However, higher methylation efficiency (MeHg/Hgt ratio) was found in CS+SBFL counterbalancing this benefit. Abundances of specific phospholipid fatty acids suggest the presence of sulfate-reducing bacteria, which are considered as primary Hg methylators. The results indicate that both BC and SBFL have the potential to curtail the release of Hgt from inundated soils, while SBFL was more efficient. However, these amendments had no marked effect on the MeHg and EtHg concentrations. Therefore, further research should be conducted to identify soil additives that are capable to reduce the release and formation of these Hg species.
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Affiliation(s)
- Felix Beckers
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany
| | - Sibylle Mothes
- UFZ Helmholtz Centre for Environmental Research, Department of Analytical Chemistry, Permoserstraße 15, 04318 Leipzig, Germany
| | - Jens Abrigata
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany
| | - Jiating Zhao
- CAS Key Laboratory of Nuclear Analytical Techniques, Key Lab for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yuxi Gao
- CAS Key Laboratory of Nuclear Analytical Techniques, Key Lab for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; Department of Environment, Energy & Geoinformatics, Sejong University, 98 Gunja-Dong, Guangjin-Gu, Seoul, South Korea.
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156
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Osterwalder S, Huang JH, Shetaya WH, Agnan Y, Frossard A, Frey B, Alewell C, Kretzschmar R, Biester H, Obrist D. Mercury emission from industrially contaminated soils in relation to chemical, microbial, and meteorological factors. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 250:944-952. [PMID: 31085481 DOI: 10.1016/j.envpol.2019.03.093] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/21/2019] [Accepted: 03/22/2019] [Indexed: 06/09/2023]
Abstract
The Minamata Convention entered into force in 2017 with the aim to phase-out the use of mercury (Hg) in manufacturing processes such as the chlor-alkali or vinyl chloride monomer production. However, past industrial use of Hg had already resulted in extensive soil pollution, which poses a potential environmental threat. We investigated the emission of gaseous elemental mercury (Hg0) from Hg polluted soils in settlement areas in the canton of Valais, Switzerland, and its impact on local air Hg concentrations. Most soil Hg was found as soil matrix-bound divalent Hg (HgII). Elemental mercury (Hg0) was undetectable in soils, yet we observed substantial Hg0 emission (20-1392 ng m-2 h-1) from 27 soil plots contaminated with Hg (0.2-390 mg Hg kg-1). The emissions of Hg0 were calculated for 1274 parcels covering an area of 8.6 km2 of which 12% exceeded the Swiss soil remediation threshold of 2 mg Hg kg-1. The annual Hg0 emission from this area was approximately 6 kg a-1, which is almost 1% of the total atmospheric Hg emissions in Switzerland based on emission inventory estimates. Our results show a higher abundance of Hg resistance genes (merA) in soil microbial communities with increasing soil Hg concentrations, indicating that biotic reduction of HgII is likely an important pathway to form volatile Hg0 in these soils. The total soil Hg pool in the top 20 cm of the investigated area was 4288 kg; hence, if not remediated, these contaminated soils remain a long-term source of atmospheric Hg, which is prone to long-range atmospheric transport.
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Affiliation(s)
- Stefan Osterwalder
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden.
| | - Jen-How Huang
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland
| | - Waleed H Shetaya
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland; Air Pollution Research Department, Environmental Research Division, National Research Centre, Dokki, Giza 12622, Egypt
| | - Yannick Agnan
- Sorbonne Université, CNRS, EPHE, UMR Metis, 75252 Paris, France
| | - Aline Frossard
- Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
| | - Beat Frey
- Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
| | - Christine Alewell
- Environmental Geosciences, University of Basel, 4056 Basel, Switzerland
| | - Ruben Kretzschmar
- Institute of Biogeochemistry and Pollutant Dynamics, CHN, ETH Zürich, Zürich, Switzerland
| | - Harald Biester
- Institut für Geökologie, AG Umweltgeochemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Daniel Obrist
- Department of Environmental, Earth and Atmospheric Sciences, University of Massachusetts, Lowell, MA 01854, USA
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157
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Astudillo-García C, Hermans SM, Stevenson B, Buckley HL, Lear G. Microbial assemblages and bioindicators as proxies for ecosystem health status: potential and limitations. Appl Microbiol Biotechnol 2019; 103:6407-6421. [DOI: 10.1007/s00253-019-09963-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/03/2019] [Accepted: 06/04/2019] [Indexed: 01/04/2023]
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158
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Szekeres LI, Bálint S, Galbács G, Kálomista I, Kiss T, Larsen FH, Hemmingsen L, Jancsó A. Hg 2+ and Cd 2+ binding of a bioinspired hexapeptide with two cysteine units constructed as a minimalistic metal ion sensing fluorescent probe. Dalton Trans 2019; 48:8327-8339. [PMID: 31111849 DOI: 10.1039/c9dt01141b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hg2+ and Cd2+ complexation of a short hexapeptide, Ac-DCSSCY-NH2 (DY), was studied by pH-potentiometry, UV and NMR spectroscopy and fluorimetry in aqueous solutions and the Hg2+-binding ability of the ligand was also described in an immobilized form, where the peptides were anchored to a hydrophilic resin. Hg2+ was demonstrated to form a 1 : 1 complex with the ligand even at pH = 2.0 while Cd2+ coordination by the peptide takes place only above pH ∼ 3.5. Both metal ions form bis-ligand complexes by the coordination of four Cys-thiolates at ligand excess above pH ∼ 5.5 (Cd2+) and 7.0 (Hg2+). Fluorescence studies demonstrated a Hg2+ induced concentration-dependent quenching of the Tyr fluorescence until a 1 : 1 Hg2+ : DY ratio. The fluorescence emission intensity decreases linearly with the increasing Hg2+ concentration in a range of over two orders of magnitude. The fact that this occurs even in the presence of 1.0 eq. of Cd2+ per ligand reflects a complete displacement of the latter metal ion by Hg2+ from its peptide-bound form. The immobilized peptide was also shown to bind Hg2+ very efficiently even from samples at pH = 2.0. However, the existence of lower affinity binding sites was also demonstrated by binding of more than 1.0 eq. of Hg2+ per immobilized DY molecule under Hg2+-excess conditions. Experiments performed with a mixture of four metal ions, Hg2+, Cd2+, Zn2+ and Ni2+, indicate that this molecular probe may potentially be used in Hg2+-sensing systems under acidic conditions for the measurement of μM range concentrations.
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Affiliation(s)
- Levente I Szekeres
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Sára Bálint
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Gábor Galbács
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Ildikó Kálomista
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Tamás Kiss
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Flemming H Larsen
- Department of Food Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C, Denmark
| | - Lars Hemmingsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Attila Jancsó
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
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159
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Periphyton and Flocculent Materials Are Important Ecological Compartments Supporting Abundant and Diverse Mercury Methylator Assemblages in the Florida Everglades. Appl Environ Microbiol 2019; 85:AEM.00156-19. [PMID: 31028023 DOI: 10.1128/aem.00156-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 04/19/2019] [Indexed: 12/21/2022] Open
Abstract
Mercury (Hg) methylation in the Florida Everglades is of great environmental concern because of its adverse effects on human and wildlife health through biomagnification in aquatic food webs. Periphyton and flocculant materials (floc) overlaying peat soil are important ecological compartments producing methylmercury (MeHg) in this ecosystem. These compartments retain higher concentrations of MeHg than did soil at study sites across nutrient and/or sulfate gradient(s). To better understand what controls Hg methylation in these compartments, the present study explored the structures and abundances of Hg methylators using genes hgcAB as biomarkers. The hgcA sequences indicated that these compartments hosted a high diversity of Hg methylators, including Deltaproteobacteria, Chloroflexi, Firmicutes, and Methanomicrobia, with community compositions that differed between these habitats. The copy numbers of hgcAB quantified by quantitative PCR revealed that floc and soil supported higher numbers of Hg methylators than periphyton in the Everglades ecosystem. The abundance of Hg methylators was strongly positively correlated with concentrations of carbon and nutrients (e.g., phosphorus and nitrogen) according to redundancy analysis. Strong correlations were also observed among numbers of sulfate reducers, methanogens, and the dominant hgcAB-carrying groups, suggesting that hgcAB would spread primarily through the growth of those assemblages. The abundances of Hg methylators were weakly negatively correlated to MeHg concentrations, suggesting that the size of this population would not solely determine the final concentrations of MeHg in the ecological compartments studied. This study extends the knowledge regarding the distribution of diverse potential mercury methylators in different environmental compartments in a wetland of national concern.IMPORTANCE Methylmercury is a potent neurotoxin that impacts the health of humans and wildlife. Most mercury in wetlands such as the Florida Everglades enters as inorganic mercury via atmospheric deposition, some of which is transformed to the more toxic methylmercury through the activities of anaerobic microorganisms. We investigated the numbers and phylogenetic diversity of hgcAB, genes that are linked to mercury methylation, in the soil, floc, and periphyton in areas of the Everglades with different sulfate and nutrient concentrations. Soil harbored relatively high numbers of cells capable of methylating mercury; however, little detectable methylmercury was present in soil. The greatest concentrations of methylmercury were found in floc and periphyton. The dominant methylators in those compartments included methanogens and Syntrophobacteriales This work provides significant insight into the microbial processes that control methylation and form the basis for accumulation through the food chain in this important environment.
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160
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Padalkar PP, Chakraborty P, Chennuri K, Jayachandran S, Sitlhou L, Nanajkar M, Tilvi S, Singh K. Molecular characteristics of sedimentary organic matter in controlling mercury (Hg) and elemental mercury (Hg 0) distribution in tropical estuarine sediments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:592-601. [PMID: 30856569 DOI: 10.1016/j.scitotenv.2019.02.353] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
Sedimentary organic matter (SOM) plays an important role in hosting and reducing HgII in marine/estuarine sediment. This study provides a better understanding on the influence of nature of SOM, in regulating sedimentary mercury (Hg) and elemental mercury (Hg0) distribution, and speciation in the Zuari and Mandovi Estuaries that are representative of monsoon fed tropical estuaries, located in the central west coast of India. Salinity of the overlying water column controlled the physical and chemical characteristics of SOM in the estuarine systems. The high molecular weight (MW) SOM dominated at the mid and upstream (low salinity region) of the estuaries, whereas, the low MW SOM prevailed at the downstream (high salinity region). Sediment Hg showed more affinity towards the SOM of high MW. Increasing MW of SOM increased total sedimentary HgT in both the estuaries. SOM with low MW in the estuarine sediment displayed a negative relationship with the sediment Hg concentration. Distribution of Hg0 concentration in the estuarine sediment suggests that reduction of HgII in presence low MW SOM was a dominant process. It was also found that distribution and speciation of Hg0 in the estuarine sediment depends on the quantity, quality of the SOM, and the total sediment Hg loading. This study demonstrated that the competition between Hg-SOM complexation and HgII reduction by SOM controls HgII/Hg0 distribution in tropical estuarine sediment systems.
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Affiliation(s)
- Prasad P Padalkar
- Geological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India
| | - Parthasarathi Chakraborty
- Geological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India; Centre for Oceans, Rivers, Atmosphere and Land Sciences, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India.
| | - Kartheek Chennuri
- Geological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India
| | - Saranya Jayachandran
- Geological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India
| | - Lamjahao Sitlhou
- Geological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India
| | - Mandar Nanajkar
- Business Development Group, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India
| | - Supriya Tilvi
- Chemical Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India
| | - Keisham Singh
- Chemical Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India
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An J, Zhang L, Lu X, Pelletier DA, Pierce EM, Johs A, Parks JM, Gu B. Mercury Uptake by Desulfovibrio desulfuricans ND132: Passive or Active? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6264-6272. [PMID: 31075193 DOI: 10.1021/acs.est.9b00047] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Recent studies have identified HgcAB proteins as being responsible for mercury [Hg(II)] methylation by certain anaerobic microorganisms. However, it remains controversial whether microbes take up Hg(II) passively or actively. Here, we examine the dynamics of concurrent Hg(II) adsorption, uptake, and methylation by both viable and inactivated cells (heat-killed or starved) or spheroplasts of the sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 in laboratory incubations. We show that, without addition of thiols, >60% of the added Hg(II) (25 nM) was taken up passively in 48 h by live and inactivated cells and also by cells treated with the proton gradient uncoupler, carbonylcyanide-3-chlorophenylhydrazone (CCCP). Inactivation abolished Hg(II) methylation, but the cells continued taking up Hg(II), likely through competitive binding or ligand exchange of Hg(II) by intracellular proteins or thiol-containing cellular components. Similarly, treatment with CCCP impaired the ability of spheroplasts to methylate Hg(II) but did not stop Hg(II) uptake. Spheroplasts showed a greater capacity to adsorb Hg(II) than whole cells, and the level of cytoplasmic membrane-bound Hg(II) correlated well with MeHg production, as Hg(II) methylation is associated with cytoplasmic HgcAB. Our results indicate that active metabolism is not required for cellular Hg(II) uptake, thereby providing an improved understanding of Hg(II) bioavailability for methylation.
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Affiliation(s)
- Jing An
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Lijie Zhang
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Xia Lu
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Dale A Pelletier
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Eric M Pierce
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Alexander Johs
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Jerry M Parks
- Biosciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Baohua Gu
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Department of Biosystems Engineering and Soil Science , University of Tennessee , Knoxville , Tennessee 37996 , United States
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162
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Lima FRD, Martins GC, Silva AO, Vasques ICF, Engelhardt MM, Cândido GS, Pereira P, Reis RHCL, Carvalho GS, Windmöller CC, Moreira FMS, Guilherme LRG, Marques JJ. Critical mercury concentration in tropical soils: Impact on plants and soil biological attributes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 666:472-479. [PMID: 30802662 DOI: 10.1016/j.scitotenv.2019.02.216] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/12/2019] [Accepted: 02/13/2019] [Indexed: 06/09/2023]
Abstract
Mercury is a toxic element that becomes a problem when present at high concentrations in soils. Mercury toxicity in soils varies depending on chemical species, concentration, exposure routes, and organism vulnerability. There is little information regarding the toxicity of Hg in tropical soils, especially for establishing safe levels of this pollutant. The purpose of this study was to investigate Hg concentrations in two tropical soils and their effect on oats and common beans, as well as on soil biological attributes. The experiment was carried out in a greenhouse, following ISO 11.269-2 and OECD-208 guidelines. Oat and common bean were cultivated in a Typic Hapludox (TyHpx) and Rhodic Acrudox (RhAcx) contaminated with HgCl2 at the following concentrations: 0, 2.5, 5.0, 10.0, 20.0, 40.0, and 80.0 mg of Hg kg-1 of dry soil. The biological variables analyzed were seedling emergence, vegetative growth, chlorophyll content (SPAD index), gas exchange (photosynthetic rate, internal CO2 concentration, transpiration rate, and stomatal conductance), and Hg concentration and accumulation in shoot dry matter. Microbial biomass carbon, soil basal respiration, and metabolic quotient (qCO2) were also analyzed. Due to the sorptive characteristics of TyHpx, it had higher Hg concentrations than RhAcx. Mercury showed toxic effects on both oat and common bean species. However, common bean was affected only at concentrations higher than 20 mg kg-1. The microbial community showed high sensitivity to soil Hg concentrations, but external factors, such as the plant species cultivated, influenced the sensitivity of the community. The microbiota was most sensitive in pots with common bean, and this effect was more pronounced at low clay and low organic matter contents (TyHpx). In this study, the concentration of 0.36 mg kg-1 was critical for Hg in these soils, based on its deleterious effects on oat and common bean and on biological soil attributes.
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Affiliation(s)
- F R D Lima
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - G C Martins
- Instituto Tecnológico Vale, Belém 66055-090, Pará State, Brazil
| | - A O Silva
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - I C F Vasques
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - M M Engelhardt
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - G S Cândido
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - P Pereira
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - R H C L Reis
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - G S Carvalho
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - C C Windmöller
- Departamento de Química, ICEX, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais State, Brazil
| | - F M S Moreira
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - L R G Guilherme
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil
| | - J J Marques
- Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras 37200-000, Minas Gerais State, Brazil.
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Singh DK, Lingaswamy B, Koduru TN, Nagu PP, Jogadhenu PSS. A putative merR family transcription factor Slr0701 regulates mercury inducible expression of MerA in the cyanobacterium Synechocystis sp. PCC6803. Microbiologyopen 2019; 8:e00838. [PMID: 31094100 PMCID: PMC6741143 DOI: 10.1002/mbo3.838] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/24/2019] [Accepted: 02/26/2019] [Indexed: 11/23/2022] Open
Abstract
In cyanobacteria, genes conferring mercury resistance are not organized as mer‐operon, unlike in other bacterial phyla. Synechocystis contains only a putative MerR regulator, Slr0701, and a mercury reductase, MerA, located aside from each other in the genome. The slr0701‐mutant showed reduction in photosynthetic activity and reduced tolerance to mercury compared to the wild‐type. The incubation of wild‐type cells with HgCl2 resulted in the upregulation of slr0701 and slr1849 genes whereas mercury‐induced expression was not observed in the slr0701‐mutant. Slr0701 binds to a conserved cis‐regulatory element located in the upstream of slr1849 and slr0701 ORFs. The same element was also identified in the upstream of other cyanobacterial homologs. Slr0701 binds to cis‐regulatory element with faster association and slower dissociation rates in the presence of HgCl2. Although these genes were constitutively expressed, the addition of HgCl2 enhanced their promoter activity suggesting that mercury‐bound Slr0701 triggers induced expression of these genes. The enhanced promoter activity could be attributed to the observed secondary structural changes in Slr0701 in the presence of HgCl2. For the first time, we demonstrated the mechanism of merA regulation in a cyanobacterium, Synechocystis. Although merA and merR genes are distantly located on the cyanobacterial genome and distinct from other bacterial mer‐operons, the transcriptional regulatory mechanism is conserved.
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Affiliation(s)
- Deepak Kumar Singh
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Bantu Lingaswamy
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Tejaswi Naidu Koduru
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Prakash Prabhu Nagu
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
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164
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Du H, Ma M, Igarashi Y, Wang D. Biotic and Abiotic Degradation of Methylmercury in Aquatic Ecosystems: A Review. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:605-611. [PMID: 30603765 DOI: 10.1007/s00128-018-2530-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/18/2018] [Indexed: 05/16/2023]
Abstract
Mercury (Hg) methylation and demethylation is supposed to simultaneously exist in the environment and form a cycle, which determines the net production of methylmercury (MeHg). Exploring the mechanisms of MeHg formation and degradation, and its final fate in the natural environment is essential to understanding the biogeochemical cycle of Hg. However, MeHg demethylation has been less studied in the past years comparing with Hg methylation, particularly in anaerobic microorganisms whose demethylation role has been under-evaluated. This review described the current state of knowledge on biotic (microorganisms) and abiotic demethylation (photodegradation, chemical degradation) of MeHg. The decomposition of MeHg performed by microorganisms has been identified as two different pathways, reductive demethylation (RD) and oxidative demethylation (OD). Anaerobic and aerobic microorganisms involved in the process of RD and OD, influencing factors as well as research background and histories are systematically described in this review. It is predicted that the photodegradation mechanism, as well as anaerobic microorganisms involved in MeHg formation and degradation cycle will be the focus of future research.
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Affiliation(s)
- Hongxia Du
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
- Chongqing Key Laboratory of Bio-Resource for Bioenergy, Southwest University, Chongqing, 400715, China
| | - Ming Ma
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Yasuo Igarashi
- College of Resources and Environment, Southwest University, Chongqing, 400715, China.
- Chongqing Key Laboratory of Bio-Resource for Bioenergy, Southwest University, Chongqing, 400715, China.
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China.
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165
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Abu-Taweel GM. Neurobehavioral protective properties of curcumin against the mercury chloride treated mice offspring. Saudi J Biol Sci 2019; 26:736-743. [PMID: 31048998 PMCID: PMC6486524 DOI: 10.1016/j.sjbs.2018.10.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/29/2018] [Accepted: 10/30/2018] [Indexed: 01/21/2023] Open
Abstract
In the present investigation, the effects of mercuric chloride (HgCl2) on the neurobehavioural and neurochemical disruption in mice offspring was studied. A total of thirty pregnant mice were divided into six groups. Group II and III were received 150 and 300 ppm of curcumin respectively. Group IV was given 10 ppm of HgCl2. Group V and VI were given 10 ppm of HgCl2 with 150 and 300 ppm of curcumin respectively. In this study, treatment started from day one of pregnancy and continued until post-natal day 15 (PD 15). During weaning period, three pups in each experimental group were marked and were subjected to behavioral, physical and biochemical tests. The results revealed decreased body weight, delayed hair growth and eye opening. HgCl2 treated pups taken more time in righting, rotating reflexes to return to normal placement, cliff avoidance compared to that of control group. HgCl2 exposed pups showed memory and learning deficits. Anxiety behavior in treating pups was increased. Biochemical investigations showed decreased level of dopamine (DA), serotonin (5-HT) and acetylcholinesterase (AChE) in forebrain of treated pups compared to the control and curcumin groups. The protective effect of curcumin doses were significant compared to HgCl2 group. The results indicated that the administration of curcumin showed effective activity towards biochemical and behavioral disorders obtained with the HgCl2 treated animals. Overall, the curcumin administration revealed increased cognetion and anxiety behaviors in the treated animals. Conclusively, curcumin has a good benefits for health which can use to avoid toxicants such as Hg and other heavy metals.
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166
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Li H, Lin X, Zhao J, Cui L, Wang L, Gao Y, Li B, Chen C, Li YF. Intestinal Methylation and Demethylation of Mercury. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:597-604. [PMID: 30515547 DOI: 10.1007/s00128-018-2512-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 11/30/2018] [Indexed: 05/20/2023]
Abstract
Mercury (Hg) is a global pollutant, which is linked with different diseases. The methylation of Hg and demethylation of methylmercury (MeHg) in the environment were extensively studied and summarized; however, the transformation of Hg in the intestine is less presented. In this review, the research progress and the perspectives on the intestinal transformation of Hg were discussed. Studies found that MeHg could be formed when exposed to inorganic Hg by the gut microbiota in aquatic organisms, terrestrial invertebrates, and mammals, etc. hgcAB genes could be used as indicators for predicting Hg methylation potential. In vitro studies using fecal specimen, intestinal contents, and the isolated intestinal microbes confirmed the intestinal demethylation of MeHg. The investigation on the effects of Hg exposure to the abundance and diversity of intestinal microbes and their metabolites could shed light on the mechanism of the toxicity of Hg, especially the neurotoxicity of MeHg, which deserves further study.
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Affiliation(s)
- Hong Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoying Lin
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Liwei Cui
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Liming Wang
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Bai Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Chunying Chen
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing, 100191, China
| | - Yu-Feng Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
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167
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Multiple Lines of Evidences Reveal Mechanisms Underpinning Mercury Resistance and Volatilization by Stenotrophomonas sp. MA5 Isolated from the Savannah River Site (SRS), USA. Cells 2019; 8:cells8040309. [PMID: 30987227 PMCID: PMC6523443 DOI: 10.3390/cells8040309] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/29/2019] [Accepted: 03/30/2019] [Indexed: 11/17/2022] Open
Abstract
A largely understudied microbially mediated mercury (Hg) bioremediative pathway includes the volatilization of Hg2+ to Hg0. Therefore, studies on Hg resistant bacteria (HgR), isolated from historically long-term contaminated environments, can serve as models to understand mechanisms underpinning Hg cycling. Towards this end, a mercury resistant bacterial strain, identified as Stenotrophomonas sp., strain MA5, was isolated from Mill Branch on the Savannah River Site (SRS); an Hg-impacted ecosystem. Minimum inhibitory concentration (MIC) analysis showed Hg resistance of up to 20 µg/mL by MA5 with 95% of cells retaining viability. Microcosm studies showed that the strain depleted more than 90% of spiked Hg2+ within the first 24 h of growth and the detection of volatilized mercury indicated that the strain was able to reduce Hg2+ to Hg0. To understand molecular mechanisms of Hg volatilization, a draft whole genome sequence was obtained, annotated and analyzed, which revealed the presence of a transposon-derived mer operon (merRTPADE) in MA5, known to transport and reduce Hg2+ into Hg0. Based on the whole genome sequence of strain MA5, qRT-PCR assays were designed on merRTPADE, we found a ~40-fold higher transcription of mer T, P, A, D and E when cells were exposed to 5 µg/mL Hg2+. Interestingly, strain MA5 increased cellular size as a function of increasing Hg concentrations, which is likely an evolutionary response mechanism to cope with Hg stress. Moreover, metal contaminated environments are shown to co-select for antibiotic resistance. When MA5 was screened for antibiotic resistance, broad resistance against penicillin, streptomycin, tetracycline, ampicillin, rifampicin, and erythromycin was found; this correlated with the presence of multiple gene determinants for antibiotic resistance within the whole genome sequence of MA5. Overall, this study provides an in-depth understanding of the underpinnings of Stenotrophomonas-mercury interactions that facilitate cellular survival in a contaminated soil habitat.
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168
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Superoxide Dismutase and Pseudocatalase Increase Tolerance to Hg(II) in Thermus thermophilus HB27 by Maintaining the Reduced Bacillithiol Pool. mBio 2019; 10:mBio.00183-19. [PMID: 30940703 PMCID: PMC6445937 DOI: 10.1128/mbio.00183-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermus thermophilus is a deep-branching thermophilic aerobe. It is a member of the Deinococcus-Thermus phylum that, together with the Aquificae, constitute the earliest branching aerobic bacterial lineages; therefore, this organism serves as a model for early diverged bacteria (R. K. Hartmann, J. Wolters, B. Kröger, S. Schultze, et al., Syst Appl Microbiol 11:243–249, 1989, https://doi.org/10.1016/S0723-2020(89)80020-7) whose natural heated habitat may contain mercury of geological origins (G. G. Geesey, T. Barkay, and S. King, Sci Total Environ 569-570:321–331, 2016, https://doi.org/10.1016/j.scitotenv.2016.06.080). T. thermophilus likely arose shortly after the oxidation of the biosphere 2.4 billion years ago. Studying T. thermophilus physiology provides clues about the origin and evolution of mechanisms for mercury and oxidative stress responses, the latter being critical for the survival and function of all extant aerobes. Mercury (Hg) is a widely distributed, toxic heavy metal with no known cellular role. Mercury toxicity has been linked to the production of reactive oxygen species (ROS), but Hg does not directly perform redox chemistry with oxygen. How exposure to the ionic form, Hg(II), generates ROS is unknown. Exposure of Thermus thermophilus to Hg(II) triggered ROS accumulation and increased transcription and activity of superoxide dismutase (Sod) and pseudocatalase (Pcat); however, Hg(II) inactivated Sod and Pcat. Strains lacking Sod or Pcat had increased oxidized bacillithiol (BSH) levels and were more sensitive to Hg(II) than the wild type. The ΔbshA Δsod and ΔbshA Δpcat double mutant strains were as sensitive to Hg(II) as the ΔbshA strain that lacks bacillithiol, suggesting that the increased sensitivity to Hg(II) in the Δsod and Δpcat mutant strains is due to a decrease of reduced BSH. Treatment of T. thermophilus with Hg(II) decreased aconitase activity and increased the intracellular concentration of free Fe, and these phenotypes were exacerbated in Δsod and Δpcat mutant strains. Treatment with Hg(II) also increased DNA damage. We conclude that sequestration of the redox buffering thiol BSH by Hg(II), in conjunction with direct inactivation of ROS-scavenging enzymes, impairs the ability of T. thermophilus to effectively metabolize ROS generated as a normal consequence of growth in aerobic environments.
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169
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Bioconversion of Hg and Molecular Characterization of merA and merB Gene in a Clone Constructed by Culture Independent Technique. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2019. [DOI: 10.22207/jpam.13.1.55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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170
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Bioremediation of Mercury through Encapsulation of the Clone Carrying Meroperon. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2019. [DOI: 10.22207/jpam.13.1.62] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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171
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Huang ZS, Wei ZS, Xiao XL, Tang MR, Li BL, Zhang X. Simultaneous mercury oxidation and NO reduction in a membrane biofilm reactor. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 658:1465-1474. [PMID: 30678005 DOI: 10.1016/j.scitotenv.2018.12.105] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 11/13/2018] [Accepted: 12/08/2018] [Indexed: 06/09/2023]
Abstract
This work demonstrates bacterial oxidation of mercury (Hg0) coupled to nitric oxide (NO) reduction in a denitrifying membrane biofilm reactor (MBfR). In 93 days' operation, Hg0 and NO removal efficiency attained 90.7% and 74.1%, respectively. Thauera, Pseudomonas, Paracoccus and Pannonibacter played dual roles as Hg0 oxidizers and denitrifiers simultaneously. Denitrifying bacteria and the potential mercury resistant bacteria dominated the bacterial community. Denitrification-related genes (norB, norC, norD, norE, norQ and norV) and enzymatic Hg0 oxidation-related genes (katG, katE) were responsible for bacterial oxidation of Hg0 and NO reduction, as shown by metagenomic sequencing. XPS, HPLC-ICP-MS and SEM-EDS indicated the formation of a stable mercuric species (Hg2+) reasulting from Hg0 oxidation in the biofilm. Bacterial oxidation of Hg0 was coupled to NO reduction in which Hg0 served as the initial electron donor while NO served as the terminal electron acceptor and thereby redox between Hg0 and NO was formed. MBfR was capable of both Hg0 bio-oxidation and denitrifying NO reduction. This research opens up new possibilities for application of MBfR to simultaneous flue gas demercuration and denitration.
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Affiliation(s)
- Z S Huang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - Z S Wei
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China.
| | - X L Xiao
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - M R Tang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - B L Li
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - X Zhang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
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172
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Lee CS, Fisher NS. Microbial generation of elemental mercury from dissolved methylmercury in seawater. LIMNOLOGY AND OCEANOGRAPHY 2019; 64:679-693. [PMID: 31105337 PMCID: PMC6519744 DOI: 10.1002/lno.11068] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Elemental mercury (Hg0) formation from other mercury species in seawater results from photoreduction and microbial activity, leading to possible evasion from seawater to overlying air. Microbial conversion of monomethylmercury (MeHg) to Hg0 in seawater remains unquantified. A rapid radioassay method was developed using gamma-emitting 203Hg as a tracer to evaluate Hg0 production from Hg(II) and MeHg in the low pM range. Bacterioplankton assemblages in Atlantic surface seawater and Long Island Sound water were found to rapidly produce Hg0, with production rate constants being directly related to bacterial biomass and independent of dissolved Hg(II) and MeHg concentrations. About 32% of Hg(II) and 19% of MeHg were converted to Hg0 in 4 d in Atlantic surface seawater containing low bacterial biomass, and in Long Island Sound water with higher bacterial biomass, 54% of Hg(II) and 8% of MeHg were transformed to Hg0. Decreasing temperatures from 24°C to 4°C reduced Hg0 production rates cell-1 from Hg(II) 3.3 times as much as from a MeHg source. Because Hg0 production rates were linearly related to microbial biomass and temperature, and microbial mercuric reductase was detected in our field samples, we inferred that microbial metabolic activities and enzymatic reactions primarily govern Hg0 formation in subsurface waters where light penetration is diminished.
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173
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de Araújo LCA, da Purificação-Júnior AF, da Silva SM, Lopes ACS, Veras DL, Alves LC, Dos Santos FB, Napoleão TH, Dos Santos Correia MT, da Silva MV, Oliva MLV, de Oliveira MBM. In vitro evaluation of mercury (Hg 2+) effects on biofilm formation by clinical and environmental isolates of Klebsiella pneumoniae. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 169:669-677. [PMID: 30500736 DOI: 10.1016/j.ecoenv.2018.11.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/05/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
The increase in urbanization and industrialization has contributed to the contamination of different environments by means of xenobiotic compounds, such as heavy metals, causing changes in microbial communities. Among these metals, the Mercury (Hg2+) is one the most prevalent toxic metals for the environment The present study aimed to evaluate the effect of mercury on the formation of biofilm by environmental (collected from urban stream water) and clinical isolates of Klebsiella pneumoniae. In addition, antibiotic resistance, virulence factors, and genetic diversity were investigated. Taxonomic identity of eight isolates (one reference, two clinical, and five environmental isolates) was performed by MALDI-TOF-MS, while the antibiotic susceptibility profile was assessed by the disc diffusion method. The ability to form biofilms was evaluated by culture on Congo red agar and by crystal violet staining. Biofilm structure was analyzed by scanning electron microscopy. The hydrophobicity profile and the presence of the virulence genes cps, fimH, and mrkD was investigated. The presence of merA and its relationship with antimicrobial resistance were also assessed. The identity of all isolates was confirmed by MALDI-TOF-MS, and different profiles of resistance to mercury and antibiotics as well as of biofilm formation were identified for the clinical and environmental isolates. All isolates were hydrophilic and positive for the virulence genes cps, fimH, and mrkD; only the clinical isolate K36-A2 was positive for merA. The diversity of the isolates was confirmed by ERIC-PCR, which revealed high heterogeneity among the isolates. In conclusion, the data demonstrate that the investigated isolates present different responses to exposure to Hg2+ and correspond to distinct populations of K. pneumoniae disseminated in the investigated environment. The data obtained in this work will aid in understanding the mechanisms of survival of this pathogen under adverse conditions.
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Affiliation(s)
| | | | - Sivoneide Maria da Silva
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Ana Catarina Souza Lopes
- Departamento de Medicina Tropical, Centro de Ciências da Saúde, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Dyana Leal Veras
- Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Pernambuco, Brazil
| | - Luiz Carlos Alves
- Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Pernambuco, Brazil
| | - Fábio Brayner Dos Santos
- Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Pernambuco, Brazil
| | - Thiago Henrique Napoleão
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | | | - Márcia Vanusa da Silva
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Maria Luiza Vilela Oliva
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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174
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Asaduzzaman A, Riccardi D, Afaneh AT, Cooper CJ, Smith JC, Wang F, Parks JM, Schreckenbach G. Environmental Mercury Chemistry - In Silico. Acc Chem Res 2019; 52:379-388. [PMID: 30689347 DOI: 10.1021/acs.accounts.8b00454] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Mercury (Hg) is a global environmental contaminant. Major anthropogenic sources of Hg emission include gold mining and the burning of fossil fuels. Once deposited in aquatic environments, Hg can undergo redox reactions, form complexes with ligands, and adsorb onto particles. It can also be methylated by microorganisms. Mercury, especially its methylated form methylmercury, can be taken up by organisms, where it bioaccumulates and biomagnifies in the food chain, leading to detrimental effects on ecosystem and human health. In support of the recently enforced Minamata Convention on Mercury, a legally binding international convention aimed at reducing the anthropogenic emission of-and human exposure to-Hg, its global biogeochemical cycle must be understood. Thus, a detailed understanding of the molecular-level interactions of Hg is crucial. The ongoing rapid development of hardware and methods has brought computational chemistry to a point that it can usefully inform environmental science. This is particularly true for Hg, which is difficult to handle experimentally due to its ultratrace concentrations in the environment and its toxicity. The current account provides a synopsis of the application of computational chemistry to filling several major knowledge gaps in environmental Hg chemistry that have not been adequately addressed experimentally. Environmental Hg chemistry requires defining the factors that determine the relative affinities of different ligands for Hg species, as they are critical for understanding its speciation, transformation and bioaccumulation in the environment. Formation constants and the nature of bonding have been determined computationally for environmentally relevant Hg(II) complexes such as chlorides, hydroxides, sulfides and selenides, in various physical phases. Quantum chemistry has been used to determine the driving forces behind the speciation of Hg with hydrochalcogenide and halide ligands. Of particular importance is the detailed characterization of solvation effects. Indeed, the aqueous phase reverses trends in affinities found computationally in the gas phase. Computation has also been used to investigate complexes of methylmercury with (seleno)amino acids, providing a molecular-level understanding of the toxicological antagonism between Hg and selenium (Se). Furthermore, evidence is emerging that ice surfaces play an important role in Hg transport and transformation in polar and alpine regions. Therefore, the diffusion of Hg and its ions through an idealized ice surface has been characterized. Microorganisms are major players in environmental mercury cycling. Some methylate inorganic Hg species, whereas others demethylate methylmercury. Quantum chemistry has been used to investigate catalytic mechanisms of enzymatic Hg methylation and demethylation. The complex interplay between the myriad chemical reactions and transport properties both in and outside microbial cells determines net biogeochemical cycling. Prospects for scaling up molecular work to obtain a mechanistic understanding of Hg cycling with comprehensive multiscale biogeochemical modeling are also discussed.
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Affiliation(s)
- Abu Asaduzzaman
- Department of Chemistry, University of Manitoba, Winnipeg, MB Canada, R3T 2N2
- School of Science, Engineering and Technology, Penn State Harrisburg, 777 West Harrisburg Pike, Middletown, Pennsylvania 17057, United States
| | - Demian Riccardi
- University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee Knoxville, Knoxville, Tennessee 37996, United States
| | - Akef T. Afaneh
- Department of Chemistry, University of Manitoba, Winnipeg, MB Canada, R3T 2N2
- Department of Chemistry, Faculty of Science, Al-Balqa Applied University, P.O. Box 19117,
postal code 19117, Al-Salt, Jordan
| | - Connor J. Cooper
- Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jeremy C. Smith
- University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee Knoxville, Knoxville, Tennessee 37996, United States
| | - Feiyue Wang
- Centre for Earth Observation Science and Department of Environment and Geography, University of Manitoba, Winnipeg, MB Canada, R3T 2N2
| | - Jerry M. Parks
- University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
- Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Georg Schreckenbach
- Department of Chemistry, University of Manitoba, Winnipeg, MB Canada, R3T 2N2
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175
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Karmakar R, Bindiya S, Hariprasad P. Convergent evolution in bacteria from multiple origins under antibiotic and heavy metal stress, and endophytic conditions of host plant. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 650:858-867. [PMID: 30308860 DOI: 10.1016/j.scitotenv.2018.09.078] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 06/08/2023]
Abstract
The focus of this work is to study the convergent evolution in bacteria from multiple origins under antibiotic and heavy metal stress, and endophytic conditions of host plant cultivated on the Yamuna river bank. Forty-one endophytic bacteria (EB) were isolated from green leafy vegetables (GLV's) and were found to be resistant to a wide range of antibiotics (AB) and heavy metals (HM) tested. Further, they showed susceptibility to Quinolones group of antibiotics, and the HM, Cadmium, Chromium, and Mercury. Twenty-seven percent of these bacteria endowed with Class I integron. The probability of co-existence of HM resistance with β‑lactams was higher, whereas quinolones group of AB recorded lesser values. These EB owned a wide array of beneficial traits, through which they improved the plant health under HM and salt stress conditions. Bacterial identity revealed the association of both plant beneficial and human pathogenic bacteria as an endophyte with GLV's. Principal component analysis showed a pattern of convergent evolution irrespective of their origin. In conclusion, under the selection pressure of AB and HM, the susceptible EB population may reduce with time and the resistant native/introduced bacteria might survive. The vertical and horizontal gene transfer between introduced and native bacteria is the crucial factor in enhancing their fitness along with the host plant to survive under abiotic stress conditions.
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Affiliation(s)
- Ruma Karmakar
- Centre for Rural Development and Technology, Indian Institute of Technology Delhi, India
| | - Shefali Bindiya
- Centre for Rural Development and Technology, Indian Institute of Technology Delhi, India
| | - P Hariprasad
- Centre for Rural Development and Technology, Indian Institute of Technology Delhi, India.
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176
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Huang Z, Wei Z, Xiao X, Tang M, Li B, Zhang X. Nitrification/denitrification shaped the mercury-oxidizing microbial community for simultaneous Hg 0 and NO removal. BIORESOURCE TECHNOLOGY 2019; 274:18-24. [PMID: 30500759 DOI: 10.1016/j.biortech.2018.11.069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 11/15/2018] [Accepted: 11/18/2018] [Indexed: 06/09/2023]
Abstract
A denitrifying/nitrifying membrane biofilm reactor for simultaneous removal of Hg0 and NO was investigated. Hg0 and NO removal efficiency attained 94.5% and 86%, respectively. The mercury-oxidizing microbial community was significantly shaped by nitrification/denitrification after the supply of gaseous Hg0and NO continuously. Dominant genera Rhodanobacter and Nitrosomonas participated in Hg0 oxidation, nitrification and denitrification simultaneously. Hg0 oxidizing bacteria (Gallionella, Rhodanobacter, Ottowia, Nitrosomonas and etc.), nitrifying bacteria (Nitrosomonas, Rhodanobacter, Diaphorobacte and etc.) and denitrifying bacteria (Nitrosomonas, Rhodanobacter, Castellaniella and etc.) co-existed in the MBfR, as shown by metagenomic sequencing. X-ray photoelectron spectroscopy (XPS) and high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) confirmed the formation of a mercuric species (Hg2+) from mercury bio-oxidation. Mechanism of mercury oxidation can be described as the bacterial oxidation of Hg0 in which Hg0 serves as electron donor, NO serves as electron donor in nitrification and electron acceptor in denitrification, oxygen serves as electron acceptor.
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Affiliation(s)
- Zhenshan Huang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - Zaishan Wei
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China.
| | - Xiaoliang Xiao
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - Meiru Tang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - Bolong Li
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
| | - Xiao Zhang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China
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177
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Naguib MM, Khairalla AS, El-Gendy AO, Elkhatib WF. Isolation and characterization of mercury-resistant bacteria from wastewater sources in Egypt. Can J Microbiol 2019; 65:308-321. [PMID: 30633555 DOI: 10.1139/cjm-2018-0379] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An important mechanism for microbial resistance to mercury is its reduction into elemental mercury (facilitated by the merA gene). Thirty-eight microbial isolates from a variety of wastewater sources in Egypt were collected. Approximately 14 of the 38 isolates exhibited not only a high degree of tolerance to mercury (up to 160 ppm) but also a high degree of resistance to other tested heavy metals (Cu, Co, Ni, and Zn). From these 14, the 10 most resistant isolates were selected for further study and were found to include 9 Gram-negative and 1 Gram-positive bacterial strains. Multi-antibiotic-resistance profiles were detected for 6 out of the 10 selected isolates. All the tested Gram-negative isolates (n = 9) harbored a plasmid-encoded merA gene. The mercury removal effectiveness for the 10 selected isolates ranged between 50% and 99.9%, among which Stenotrophomonas maltophilia ADW10 recorded the highest rate (99.9%; at an initial mercury concentration of 20 ppm). To the best of our knowledge, this is the first study to (i) demonstrate the presence of a multimetal-resistant S. maltophilia bacterium with a high mercury tolerance capacity that would make it a suitable candidate for future bioremediation efforts in heavy-metal-polluted areas in Egypt and (ii) report Pseudomonas otitidis as one of the mercury-resistant bacteria.
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Affiliation(s)
- Martha M Naguib
- a Department of Biotechnology and Life Sciences, Faculty of Post Graduate Studies for Advanced Sciences, Beni-Suef University, Beni-Suef, Egypt
| | - Ahmed S Khairalla
- b Department of Microbiology & Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt
| | - Ahmed O El-Gendy
- b Department of Microbiology & Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt
| | - Walid F Elkhatib
- c Department of Microbiology & Immunology, Faculty of Pharmacy, Ain Shams University, African Union Organization St., Abbassia 11566, Cairo, Egypt.,d Department of Microbiology and Immunology, School of Pharmacy & Pharmaceutical Industries, Badr University in Cairo, Entertainment Area, Badr City, Cairo, Egypt
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178
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Chen L, Cai Y, Feng W, Yuan L. Pillararenes as macrocyclic hosts: a rising star in metal ion separation. Chem Commun (Camb) 2019; 55:7883-7898. [PMID: 31236553 DOI: 10.1039/c9cc03292d] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Pillararenes are macrocyclic oligomers of alkoxybenzene akin to calixarenes but tethered at the 2,5-positions via methylene bridges. Benefiting from their unique pillar-shaped architecture favorable for diverse functionalization and versatile host-guest properties, pillararenes decorated with chelating groups worked excellently as supporting platforms to construct extractants or adsorbents for metal ion separation. This feature article provides a detailed summary of pillararenes in Ln/An separation by liquid-liquid extraction and heavy metal separation by solid-liquid extraction. The preorganization effect of the rigid pillararene framework has a profound impact on the extraction of metal ions, and a unique extraction mechanism is observed when employing ionic liquids as solvents. The rich host-guest chemistry of pillararenes enables construction of a wide variety of supramolecular materials as metal ion adsorbents. We also discuss the differences between pillararenes and several well-known macrocycles, with a focus on the metal-ligand coordination and its influencing factors. We hope this review will provide useful information and unleash new opportunities in this field.
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Affiliation(s)
- Lixi Chen
- Institute of Nuclear Science and Technology, Key Laboratory for Radiation Physics and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.
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179
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Mukkata K, Kantachote D, Wittayaweerasak B, Megharaj M, Naidu R. The potential of mercury resistant purple nonsulfur bacteria as effective biosorbents to remove mercury from contaminated areas. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2019. [DOI: 10.1016/j.bcab.2018.11.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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180
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Imran M, Das KR, Naik MM. Co-selection of multi-antibiotic resistance in bacterial pathogens in metal and microplastic contaminated environments: An emerging health threat. CHEMOSPHERE 2019; 215:846-857. [PMID: 30359954 DOI: 10.1016/j.chemosphere.2018.10.114] [Citation(s) in RCA: 286] [Impact Index Per Article: 57.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 10/10/2018] [Accepted: 10/16/2018] [Indexed: 05/19/2023]
Abstract
Misuse/over use of antibiotics increases the threats to human health since this is a main reason behind evolution of antibiotic resistant bacterial pathogens. However, metals such as mercury, lead, zinc, copper and cadmium are accumulating to critical concentration in the environment and triggering co-selection of antibiotic resistance in bacteria. The co-selection of metal driven antibiotic resistance in bacteria is achieved through co-resistance or cross resistance. Metal driven antibiotic resistant determinants evolved in bacteria and present on same mobile genetic elements are horizontally transferred to distantly related bacterial human pathogens. Additionally, in marine environment persistent pollutants like microplastics is recognized as a vector for the proliferation of metal/antibiotics and human pathogens. Recently published research confirmed that horizontal gene transfer between phylogenetically distinct microbes present on microplastics is much faster than free living microbes. Therefore, microplastics act as an emerging hotspot for metal driven co-selection of multidrug resistant human pathogens and pose serious threat to humans which do recreational activities in marine environment and ingest marine derived foods. Therefore, marine environment co-polluted with metal, antibiotics, human pathogens and microplastics pose an emerging health threat globally.
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Affiliation(s)
- Md Imran
- Department of Biotechnology, Goa University Taleigao Plateau, Goa, 403206, India.
| | - Kirti Ranjan Das
- Department of Biotechnology, Goa University Taleigao Plateau, Goa, 403206, India
| | - Milind Mohan Naik
- Department of Microbiology, Goa University Taleigao Plateau, Goa, 403206, India.
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181
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Yen PTH, Dang VH, Phong PH, Ha VTT. Electrochemical Characterization of Gold-Nanostructured Platinum Substrates and Application to Determination of Hg(II) at Trace Levels. CURR ANAL CHEM 2018. [DOI: 10.2174/1573411014666180320154119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Objectives:
To develop gold nanostructure on Pt substrate for detection of Hg(II) in
environment by DPASV technique. Its structure was characterized by SEM and electrochemical performance
was evaluated. The fabricated electrodes were used to measure Hg(II) samples in a concentration
range from 2 to 100 ppb.
Method:
Gold nanoparticles (AuNPs) and AuNDs were deposited on platinum substrates by applying
potential of +0.50 V for AuNPs deposition and galvanostatic of -50 mA for AuNDs/Pt in a solution
20 mM HAuCl4, 10 mM KI, 5 mM NH4Cl and 0.5 M H2SO4.The electrochemical behaviors of
AuNPs/Pt and AuNDs/Pt were examined using CV in 5 mM K3[Fe(CN)6]/0.1 M PBS solution, pH = 7
and the detection of Hg(II) was performed by DPASV.
Results:
The SEM images show that largest surface area was obtained at 120 s depositing time. Effective
surface areas (ESA) of AuNPs and AuNDs are about 1.39 and 5.19 times higher than electrode
geometric area. Calibration curves achieved with R2= 0.9978; 0.9975; 0.9973 and LOD= 0.55; 0.105
and 0.042 ppb for Au disk, AuNPs/Pt and AuNDs/Pt respectively. Reproducibility with ten measurements
of 10, 40 and 80 ppb of Hg(II), RSD (%) were 3.5, 2.8 and 1.5 respectively. No significant effect
on Hg(II) signals was found except CCu(II) with 100 times higher than CHg(II). Comparison with AAS,
data difference between the two techniques is acceptable, at only 4.34%.
Conclusion:
LOD for Hg(II) detection by AuNDs/Pt achieved 0.042 ppb with linear range of 2.0–100
ppb. Combining with a laboratory constructed galvano-potentiostat, it can be used in on-site measurement.
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Affiliation(s)
- Pham Thi Hai Yen
- Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Vu Hai Dang
- Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Pham Hong Phong
- Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Vu Thi Thu Ha
- Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Vietnam
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182
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Giri D, Bankura A, Patra SK. Poly(benzodithieno-imidazole-alt-carbazole) based π-conjugated copolymers: Highly selective and sensitive turn-off fluorescent probes for Hg2+. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.10.069] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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183
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Liu YR, Delgado-Baquerizo M, Bi L, Zhu J, He JZ. Consistent responses of soil microbial taxonomic and functional attributes to mercury pollution across China. MICROBIOME 2018; 6:183. [PMID: 30336790 PMCID: PMC6194565 DOI: 10.1186/s40168-018-0572-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 10/08/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND The ecological consequences of mercury (Hg) pollution-one of the major pollutants worldwide-on microbial taxonomic and functional attributes remain poorly understood and largely unexplored. Using soils from two typical Hg-impacted regions across China, here, we evaluated the role of Hg pollution in regulating bacterial abundance, diversity, and co-occurrence network. We also investigated the associations between Hg contents and the relative abundance of microbial functional genes by analyzing the soil metagenomes from a subset of those sites. RESULTS We found that soil Hg largely influenced the taxonomic and functional attributes of microbial communities in the two studied regions. In general, Hg pollution was negatively related to bacterial abundance, but positively related to the diversity of bacteria in two separate regions. We also found some consistent associations between soil Hg contents and the community composition of bacteria. For example, soil total Hg content was positively related to the relative abundance of Firmicutes and Bacteroidetes in both paddy and upland soils. In contrast, the methylmercury (MeHg) concentration was negatively correlated to the relative abundance of Nitrospirae in the two types of soils. Increases in soil Hg pollution correlated with drastic changes in the relative abundance of ecological clusters within the co-occurrence network of bacterial communities for the two regions. Using metagenomic data, we were also able to detect the effect of Hg pollution on multiple functional genes relevant to key soil processes such as element cycles and Hg transformations (e.g., methylation and reduction). CONCLUSIONS Together, our study provides solid evidence that Hg pollution has predictable and significant effects on multiple taxonomic and functional attributes including bacterial abundance, diversity, and the relative abundance of ecological clusters and functional genes. Our results suggest an increase in soil Hg pollution linked to human activities will lead to predictable shifts in the taxonomic and functional attributes in the Hg-impacted areas, with potential implications for sustainable management of agricultural ecosystems and elsewhere.
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Affiliation(s)
- Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Manuel Delgado-Baquerizo
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, 80309, USA
- Departamento de Biología, Geología, Física y Química Inorgánica, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933, Móstoles, Spain
| | - Li Bi
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Jun Zhu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ji-Zheng He
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
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184
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Wang Y, Yu Q, Mishra B, Schaefer JK, Fein JB, Yee N. Adsorption of Methylmercury onto Geobacter bemidijensis Bem. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:11564-11572. [PMID: 30207459 DOI: 10.1021/acs.est.8b01987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The anaerobic bacterium Geobacter bemidijensis Bem has the unique ability to both produce and degrade methylmercury (MeHg). While the adsorption of MeHg onto bacterial surfaces can affect the release of MeHg into aquatic environments as well as the uptake of MeHg for demethylation, the binding of MeHg to the bacterial envelope remains poorly understood. In this study, we quantified the adsorption of MeHg onto G. bemidijensis and applied X-ray absorption spectroscopy (XAS) to elucidate the mechanism of MeHg binding. The results showed MeHg adsorption onto G. bemidijensis cell surfaces was rapid and occurred via complexation to sulfhydryl functional groups. Titration experiments yielded cell surface sulfhydryl concentrations of 3.8 ± 0.2 μmol/g (wet cells). A one-site adsorption model with MeHg binding onto sulfhydryl sites provided excellent fits to adsorption isotherms conducted at different cell densities. The log K binding constant of MeHg onto the sulfhydryl sites was determined to be 10.5 ± 0.4. These findings provide a quantitative framework to describe MeHg binding onto bacterial cell surfaces and elucidate the importance of bacterial cells as possible carriers of adsorbed MeHg in natural aquatic systems.
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Affiliation(s)
- Yuwei Wang
- Department of Environmental Sciences , Rutgers University , New Brunswick , New Jersey 08901 , United States
| | - Qiang Yu
- Department of Civil & Environmental Engineering & Earth Sciences , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Bhoopesh Mishra
- School of Chemical and Process Engineering , University of Leeds , Leeds LS2 9JT , United Kingdom
| | - Jeffra K Schaefer
- Department of Environmental Sciences , Rutgers University , New Brunswick , New Jersey 08901 , United States
| | - Jeremy B Fein
- Department of Civil & Environmental Engineering & Earth Sciences , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Nathan Yee
- Department of Environmental Sciences , Rutgers University , New Brunswick , New Jersey 08901 , United States
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185
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Yuan QB, Zhai YF, Mao BY, Hu N. Antibiotic resistance genes and intI1 prevalence in a swine wastewater treatment plant and correlation with metal resistance, bacterial community and wastewater parameters. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 161:251-259. [PMID: 29886312 DOI: 10.1016/j.ecoenv.2018.05.049] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 04/17/2018] [Accepted: 05/22/2018] [Indexed: 05/21/2023]
Abstract
The livestock wastewater treatment plant represents an important reservoir of antibiotic resistance determinants in the environment. The study explored the prevalence of five antibiotic resistance genes (ARGs, including sulI, tetA, qnrD, mphB and mcr-1) and class 1 integron (intI1) in a typical livestock wastewater treatment plant, and analyzed their integrated association with two metal resistance genes (copA and czcA), two pathogens genes (Staphylococcus and Campylobacter), bacterial community and wastewater properties. Results indicated that all investigated genes were detected in the plant. The treatment plant could not completely remove ARGs abundances, with up to 2.2 × 104~3.7 × 108 copies/L of them remaining in the effluent. Mcr-1 was further enriched by 27-fold in the subsequent pond. The correlation analysis showed that mphB significantly correlateed with tetA and intI. Mcr-1 strongly correlated with copA. MphB and intI significantly correlated with czcA. The correlations implied a potential co-selection risk of bacterial resistant to antibiotics and metals. Redundancy analyses indicated that qnrD and mcr-1 strongly correlated with 13 and 14 bacterial genera, respectively. Most ARGs positively correlated to wastewater nutrients, indicating that an efficient reduction of wastewater nutrients would contribute to the antibiotic resistance control. The study will provide useful implications on fates and reductions of ARGs in livestock facilities and receiving environments.
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Affiliation(s)
- Qing-Bin Yuan
- College of Environment Science and Engineering, Nanjing Tech University, 211816 Nanjing, Jiangsu, China
| | - Yi-Fan Zhai
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 211816 Nanjing, Jiangsu, China
| | - Bu-Yun Mao
- College of Environment Science and Engineering, Nanjing Tech University, 211816 Nanjing, Jiangsu, China
| | - Nan Hu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 211816 Nanjing, Jiangsu, China.
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186
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Abstract
Mercury (Hg) is a global pollutant emitted primarily as gaseous Hg0 that is deposited in aquatic and terrestrial ecosystems following its oxidation to HgII. From that point, microbes play a key role in determining Hg’s fate in the environment by participating in sequestration, oxidation, reduction, and methylation reactions. A wide diversity of chemotrophic and phototrophic microbes occupying oxic and anoxic habitats are known to participate directly in Hg cycling. Over the last few years, new findings have come to light that have greatly improved our mechanistic understanding of microbe-mediated Hg cycling pathways in the environment. In this review, we summarize recent advances in microbially mediated Hg cycling and take the opportunity to compare the relatively well-studied chemotrophic pathways to poorly understood phototrophic pathways. We present how the use of genomic and analytical tools can be used to understand Hg transformations and the physiological context of recently discovered cometabolic Hg transformations supported in anaerobes and phototrophs. Finally, we propose a conceptual framework that emphasizes the role that phototrophs play in environmental Hg redox cycling and the importance of better characterizing such pathways in the face of the environmental changes currently underway.
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Affiliation(s)
- Daniel S. Grégoire
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Alexandre J. Poulain
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
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187
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Xing Z, Zhao T, Bai W, Yang X, Liu S, Zhang L. Temporal and spatial variation in the mechanisms used by microorganisms to form methylmercury in the water column of Changshou Lake. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 160:32-41. [PMID: 29783110 DOI: 10.1016/j.ecoenv.2018.05.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 04/17/2018] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
The microbiome in artificial lake water and its impact on mercury (Hg) methylation remain largely unknown. We selected the largest artificial lake in southeastern china, Changshou Lake (CSL), which has high background levels of Hg, for our investigation of Hg transformation microorganisms. Five different sections of the water column of CSL were sampled during four seasons. The water samples were subjected to analysis of geochemical parameters, various Hg species and microbiome information. High concentrations of total mercury (THg) were detected in CSL in comparison with those found in natural lakes. Significant differences in microbial community structure and Hg species abundance existed among seasons. High dissolved methyl mercury (DMeHg) formation and high bacterial richness and diversity occurred in the fall. The microbiome was dominated by Proteobacteria, Actinobacteria, Bacteroidetes, Deinococcus-Thermus and many unclassified bacteria. Significant correlations were found between seasonal bacterial communities and Hg levels. Hg methylation was strongly linked to the abundance of Cyanobacteria. Methylators, including Syntrophus, Desulfovibrio and Desulfomonile species, were detected only in samples collected in the fall. The results of enzyme functional analyses revealed that many unknown types of bacteria could also be responsible for Hg transformation. This study was the first to investigate the impact of various Hg species on the microbiome of artificial lake water. The findings of this study illuminate the role of seasonal bacteria in Hg transformation.
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Affiliation(s)
- Zhilin Xing
- Faculty of Urban Construction and Environment Engineering, Chongqing University, Chongqing 400045, China; School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Tiantao Zhao
- Faculty of Urban Construction and Environment Engineering, Chongqing University, Chongqing 400045, China; School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China.
| | - Weiyang Bai
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Xu Yang
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Shuai Liu
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Lijie Zhang
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
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188
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Igiri BE, Okoduwa SIR, Idoko GO, Akabuogu EP, Adeyi AO, Ejiogu IK. Toxicity and Bioremediation of Heavy Metals Contaminated Ecosystem from Tannery Wastewater: A Review. J Toxicol 2018; 2018:2568038. [PMID: 30363677 PMCID: PMC6180975 DOI: 10.1155/2018/2568038] [Citation(s) in RCA: 252] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/17/2018] [Accepted: 08/16/2018] [Indexed: 11/18/2022] Open
Abstract
The discharge of untreated tannery wastewater containing biotoxic substances of heavy metals in the ecosystem is one of the most important environmental and health challenges in our society. Hence, there is a growing need for the development of novel, efficient, eco-friendly, and cost-effective approach for the remediation of inorganic metals (Cr, Hg, Cd, and Pb) released into the environment and to safeguard the ecosystem. In this regard, recent advances in microbes-base heavy metal have propelled bioremediation as a prospective alternative to conventional techniques. Heavy metals are nonbiodegradable and could be toxic to microbes. Several microorganisms have evolved to develop detoxification mechanisms to counter the toxic effects of these inorganic metals. This present review offers a critical evaluation of bioremediation capacity of microorganisms, especially in the context of environmental protection. Furthermore, this article discussed the biosorption capacity with respect to the use of bacteria, fungi, biofilm, algae, genetically engineered microbes, and immobilized microbial cell for the removal of heavy metals. The use of biofilm has showed synergetic effects with many fold increase in the removal of heavy metals as sustainable environmental technology in the near future.
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Affiliation(s)
- Bernard E. Igiri
- Chemical and Biochemical Remediation Unit, Directorate of Research and Development, Nigerian Institute of Leather and Science Technology, Zaria 810001, Kaduna State, Nigeria
| | - Stanley I. R. Okoduwa
- Chemical and Biochemical Remediation Unit, Directorate of Research and Development, Nigerian Institute of Leather and Science Technology, Zaria 810001, Kaduna State, Nigeria
- Infohealth Awareness Department, SIRONigeria Global Limited, Abuja 900001, FCT, Nigeria
| | - Grace O. Idoko
- Chemical and Biochemical Remediation Unit, Directorate of Research and Development, Nigerian Institute of Leather and Science Technology, Zaria 810001, Kaduna State, Nigeria
| | - Ebere P. Akabuogu
- Chemical and Biochemical Remediation Unit, Directorate of Research and Development, Nigerian Institute of Leather and Science Technology, Zaria 810001, Kaduna State, Nigeria
| | - Abraham O. Adeyi
- Chemical and Biochemical Remediation Unit, Directorate of Research and Development, Nigerian Institute of Leather and Science Technology, Zaria 810001, Kaduna State, Nigeria
| | - Ibe K. Ejiogu
- Chemical and Biochemical Remediation Unit, Directorate of Research and Development, Nigerian Institute of Leather and Science Technology, Zaria 810001, Kaduna State, Nigeria
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189
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Chen CT, Liao YY, Salunke SB, Lin YH, Kuo TS. Directed Self-Assembly of C 4-Symmetric, Oxidovanadate-Centered, Vanadyl(V) Quadruplexes for Ba 2+- and Hg 2+-Specific Recognition, Transport, and Recovery. Inorg Chem 2018; 57:11511-11523. [PMID: 30183263 DOI: 10.1021/acs.inorgchem.8b01454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Directed assembly of loosely, Na+-bound, oxidovanadate-centered quartets of C4-symmetry from tailor-made chiral N-salicylidene-vanadyl(V) complexes, for the first time, allows for highly efficient Ba2+- or Hg2+-specific detection (by 51V NMR and VCD), transport (forming a unique helical capsule or a capped square planar complex, respectively), and green recovery from an aqueous phase containing 4 different alkaline earth ions or from at least 10 different metal ions of similar size and charge capacity into the CHCl3 layer without interference from oxa- or oxophilic ions like Mg2+, Ca2+, Cu2+, Cd2+, and Pb2+.
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Affiliation(s)
- Chien-Tien Chen
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan
| | - Yi-Ya Liao
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan
| | | | - Ya-Hui Lin
- National Taiwan Normal University , Taipei , Taiwan
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190
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Ciok A, Budzik K, Zdanowski MK, Gawor J, Grzesiak J, Decewicz P, Gromadka R, Bartosik D, Dziewit L. Plasmids of Psychrotolerant Polaromonas spp. Isolated From Arctic and Antarctic Glaciers - Diversity and Role in Adaptation to Polar Environments. Front Microbiol 2018; 9:1285. [PMID: 29967598 PMCID: PMC6015842 DOI: 10.3389/fmicb.2018.01285] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/25/2018] [Indexed: 12/23/2022] Open
Abstract
Cold-active bacteria of the genus Polaromonas (class Betaproteobacteria) are important components of glacial microbiomes. In this study, extrachromosomal replicons of 26 psychrotolerant Polaromonas strains, isolated from Arctic and Antarctic glaciers, were identified, sequenced, and characterized. The plasmidome of these strains consists of 13 replicons, ranging in size from 3,378 to 101,077 bp. In silico sequence analyses identified the conserved backbones of these plasmids, composed of genes required for plasmid replication, stable maintenance, and conjugal transfer. Host range analysis revealed that all of the identified plasmids are narrow-host-range replicons, only able to replicate in bacteria of closely related genera (Polaromonas and Variovorax) of the Comamonadaceae family. Special attention was paid to the identification of plasmid auxiliary genetic information, which may contribute to the adaptation of bacteria to environmental conditions occurring in glaciers. Detailed analysis revealed the presence of genes encoding proteins potentially involved in (i) protection against reactive oxygen species, ultraviolet radiation, and low temperatures; (ii) transport and metabolism of organic compounds; (iii) transport of metal ions; and (iv) resistance to heavy metals. Some of the plasmids also carry genes required for the molecular assembly of iron-sulfur [Fe-S] clusters. Functional analysis of the predicted heavy metal resistance determinants demonstrated that their activity varies, depending on the host strain. This study provides the first molecular insight into the mobile DNA of Polaromonas spp. inhabiting polar glaciers. It has generated valuable data on the structure and properties of a pool of plasmids and highlighted their role in the biology of psychrotolerant Polaromonas strains and their adaptation to the environmental conditions of Arctic and Antarctic glaciers.
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Affiliation(s)
- Anna Ciok
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Karol Budzik
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Marek K. Zdanowski
- Department of Antarctic Biology, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Jan Gawor
- Laboratory of DNA Sequencing and Oligonucleotide Synthesis, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Jakub Grzesiak
- Department of Antarctic Biology, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Przemyslaw Decewicz
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Robert Gromadka
- Laboratory of DNA Sequencing and Oligonucleotide Synthesis, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Dariusz Bartosik
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Lukasz Dziewit
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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191
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Petranich E, Covelli S, Acquavita A, Faganeli J, Horvat M, Contin M. Evaluation of mercury biogeochemical cycling at the sediment-water interface in anthropogenically modified lagoon environments. J Environ Sci (China) 2018; 68:5-23. [PMID: 29908744 DOI: 10.1016/j.jes.2017.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/08/2017] [Accepted: 11/10/2017] [Indexed: 05/17/2023]
Abstract
The Marano and Grado Lagoon is well known for being contaminated by mercury (Hg) from the Idrija mine (Slovenia) and the decommissioned chlor-alkali plant of Torviscosa (Italy). Experimental activities were conducted in a local fish farm to understand Hg cycling at the sediment-water interface. Both diffusive and benthic fluxes were estimated in terms of chemical and physical features. Mercury concentration in sediments (up to 6.81μg/g) showed a slight variability with depth, whereas the highest methylmercury (MeHg) values (up to 10ng/g) were detected in the first centimetres. MeHg seems to be produced and stored in the 2-3cm below the sediment-water interface, where sulphate reducing bacteria activity occurs and hypoxic-anoxic conditions become persistent for days. DMeHg in porewaters varied seasonally (from 0.1 and 17% of dissolved Hg (DHg)) with the highest concentrations in summer. DHg diffusive effluxes higher (up to 444ng/m2/day) than those reported in the open lagoon (~95ng/m2/day), whereas DMeHg showed influxes in the fish farm (up to -156ng/m2/day). The diurnal DHg and DMeHg benthic fluxes were found to be higher than the highest summer values previously reported for the natural lagoon environment. Bottom sediments, especially in anoxic conditions, seem to be a significant source of MeHg in the water column where it eventually accumulates. However, net fluxes considering the daily trend of DHg and DMeHg, indicated possible DMeHg degradation processes. Enhancing water dynamics in the fish farm could mitigate environmental conditions suitable for Hg methylation.
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Affiliation(s)
- Elisa Petranich
- Dipartimento di Matematica e Geoscienze, Università degli Studi di Trieste, Via Weiss 2, 34128 Trieste, Italy; Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via Licio Giorgieri 5, 34128 Trieste, Italy
| | - Stefano Covelli
- Dipartimento di Matematica e Geoscienze, Università degli Studi di Trieste, Via Weiss 2, 34128 Trieste, Italy; CoN.I.S.Ma. Consorzio Nazionale Interuniversitario per le Scienze del Mare, Piazzale Flaminio 9, 00196 Rome, Italy.
| | - Alessandro Acquavita
- Agenzia Regionale per la Protezione Ambientale del Friuli Venezia Giulia, ARPA FVG, Via Cairoli 14, 33057 Palmanova (Udine), Italy
| | | | - Milena Horvat
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Marco Contin
- Dipartimento di Scienze Agro-Alimentari, Ambientali e Animali, Università di Udine, Via delle Scienze 206, 33100 Udine, Italy
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192
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Naguib MM, El-Gendy AO, Khairalla AS. Microbial Diversity of Mer Operon Genes and Their Potential Rules in Mercury Bioremediation and Resistance. ACTA ACUST UNITED AC 2018. [DOI: 10.2174/1874070701812010056] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:Mercury is a toxic metal that is present in small amounts in the environment, but its level is rising steadily, due to different human activities, such as industrialization. It can reach humans through the food chain, amalgam fillings, and other sources, causing different neurological disorders, memory loss, vision impairment, and may even lead to death; making its detoxification an urgent task.Methods:Various physical and chemical mercury remediation techniques are available, which generally aim at: (i) reducing its mobility or solubility; (ii) causing its vaporization or condensation; (iii) its separation from contaminated soils. Biological remediation techniques, commonly known as bioremediation, are also another possible alternative, which is considered as cheaper than the conventional means and can be accomplished using either (i) organisms harboring themeroperon genes (merB,merA,merR,merP,merT,merD,merF,merC,merE,merHandmerG), or (ii) plants expressing metal-binding proteins. Recently, differentmerdeterminants have been genetically engineered into several organisms, including bacteria and plants, to aid in detoxification of both ionic and organic forms of mercury.Results:Bacteria that are resistant to mercury compounds have at least a mercuric reductase enzyme (MerA) that reduces Hg+2to volatile Hg0, a membrane-bound protein (MerT) for Hg+2uptake and an additional enzyme, MerB, that degrades organomercurials by protonolysis. Presence of bothmerA andmerB genes confer broad-spectrum mercury resistance. However,merA alone confers narrow spectrum inorganic mercury resistance.Conclusion:To conclude, this review discusses the importance of mercury-resistance genes in mercury bioremediation. Functional analysis ofmeroperon genes and the recent advances in genetic engineering techniques could provide the most environmental friendly, safe, effective and fantastic solution to overcome mercuric toxicity.
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193
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Kanzler CR, Lian P, Trainer EL, Yang X, Govind N, Parks JM, Graham AM. Emerging investigator series: methylmercury speciation and dimethylmercury production in sulfidic solutions. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2018; 20:584-594. [PMID: 29388993 DOI: 10.1039/c7em00533d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Alkylated mercury species (monomethylmercury, MeHg, and dimethylmercury, DMeHg) exhibit significant bioaccumulation, and pose significant risks to ecosystems and human health. Although decades of research have been devoted to understanding MeHg formation and degradation, little is known about the DMeHg formation in aquatic systems. Here, we combine complementary experimental and computational approaches to examine MeHg speciation and DMeHg formation in sulfidic aqueous solutions, with an emphasis on the formation and decomposition of the binuclear bis(methylmercuric(ii)) sulfide complex (CH3Hg)2S. Experimental data indicate that the reaction 2CH3Hg+ + HS- ⇄ (CH3Hg)2S + H+ has a log K = 26.0 ± 0.2. Thus, the binuclear (CH3Hg)2S complex is likely to be the dominant MeHg species under high MeHg concentrations typically used in experimental investigations of MeHg degradation by sulfate-reducing bacteria (SRB). Our finding of a significant abiotic removal mechanism for MeHg in sulfidic solutions through the formation of relatively insoluble (CH3Hg)2S suggests careful reexamination of reported "oxidative demethylation" of MeHg by SRB and perhaps other obligate anaerobes. We provide evidence for slow decomposition of (CH3Hg)2S to DMeHg and HgS, with a first-order rate constant k = 1.5 ± 0.4 × 10-6 h-1. Quantum chemical calculations suggest that the reaction proceeds by a novel mechanism involving rearrangement of the (CH3Hg)2S complex facilitated by strong Hg-Hg interactions that activate a methyl group for intramolecular transfer. Predictions of DMeHg formation rates under a variety of field and laboratory conditions indicate that this pathway for DMeHg formation will be significant in laboratory experiments utilizing high MeHg concentrations, favoring (CH3Hg)2S formation. In natural systems with relatively high MeHg/[H2S]T ratios (the oxic/anoxic interface, for example), DMeHg production may be observed, and warrants further investigation.
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194
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Zheng R, Wu S, Ma N, Sun C. Genetic and Physiological Adaptations of Marine Bacterium Pseudomonas stutzeri 273 to Mercury Stress. Front Microbiol 2018; 9:682. [PMID: 29675016 PMCID: PMC5895735 DOI: 10.3389/fmicb.2018.00682] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/22/2018] [Indexed: 12/18/2022] Open
Abstract
Mercury-mediated toxicity remains one of the greatest barriers against microbial survival, even though bacterial resistance to mercury compounds can occur. However, the genetic and physiological adaptations of bacteria to mercury stress still remains unclear. Here, we show that the marine bacterium Pseudomonas stutzeri 273 is resistant to 50 μM Hg2+ and removes up to 94% Hg2+ from culture. Using gene homologous recombination and complementation, we show that genes encoding Hg2+-transport proteins MerT, MerP, the mercuric reductase MerA and the regulatory protein MerD are essential for bacterial mercuric resistance when challenged with Hg2+. Further, mercury stress inhibits flagellar development, motility, chemotaxis and biofilm formation of P. stutzeri 273, which are verified by transcriptomic and physiological analyses. Surprisingly, we discover that MerF, a previously reported Hg2+-transporter, determines flagellar development, motility and biofilm formation in P. stutzeri 273 by genetic and physiological analyses. Our results strongly indicate that MerF plays an integral role in P. stutzeri 273 to develop physiological responses to mercury stress. Notably, MerF homologs are also prevalent in different human pathogens. Using this unique target may provide novel strategies to control these pathogenic bacteria, given the role of MerF in flagella and biofilm formation. In summary, our data provide an original report on MerF in bacterial physiological development and suggest that the mer in marine bacteria has evolved through progressive, sequential recruitment of novel functions over time.
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Affiliation(s)
- Rikuan Zheng
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,College of Earth Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shimei Wu
- College of Life Sciences, Qingdao University, Qingdao, China
| | - Ning Ma
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,College of Earth Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chaomin Sun
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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195
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Lee S, Kim DH, Kim KW. The enhancement and inhibition of mercury reduction by natural organic matter in the presence of Shewanella oneidensis MR-1. CHEMOSPHERE 2018; 194:515-522. [PMID: 29241125 DOI: 10.1016/j.chemosphere.2017.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 11/29/2017] [Accepted: 12/02/2017] [Indexed: 06/07/2023]
Abstract
Reduction-oxidation (Redox) processes of mercury (Hg) are of significant importance in influencing Hg speciation, bioavailability, and fate in anoxic environments where natural organic matter (NOM) and dissimilatory metal reducing bacteria (DMRB) are widely observed. However, the redox reaction between Hg and NOM, has not yet been studied in the presence of S. oneidensis MR-1 in anoxic environments. We have found that the reduction rate of mercuric mercury [Hg(II)] in the presence of Elliott soil humic acid (ESHA) was 0.02 h-1. It was faster than the rate (0.01 h-1) in the direct microbial Hg(II) reduction, suggesting that ESHA acts as an electron transfer mediator between cells and Hg, which enhances Hg(II) reduction under anoxic conditions. The overall rate of Hg(II) reduction in the presence of ESHA is determined by the rate of electron transfer from S. oneidensis MR-1 to ESHA (rate-limiting step) since the rate of electron transfer from reduced ESHA to Hg(II) was so rapid. In the reaction between S. oneidensis MR-1 and a variety of NOM analogs, the production rate of elemental mercury [Hg (0)] was linearly correlated with the free radical concentrations and aromaticities in reduced NOM analogs. However, at the high ESHA concentrations or cell contents, Hg(II) reduction might be inhibited by thiol functional groups in reduced ESHA and on cells. We suggest that the presence of NOM, cell concentration and NOM source can significantly affect the redox processes of Hg and therefore, have important implications for elucidating Hg redox processes under environmentally relevant complex conditions.
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Affiliation(s)
- Seyong Lee
- Center for Environmental Assessment Monitoring, Korea Environment Institute (KEI), 370 Sicheong-daero, Sejong, 30147, Republic of Korea
| | - Dong-Hun Kim
- Groundwater and Ecohydrology Research Center, Korea Institute of Geoscience and Mineral Resources (KIGAM), Gwahak-ro, Yuseoung-gu, Daejeon, 34132, Republic of Korea
| | - Kyoung-Woong Kim
- School of Earth Sciences & Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea.
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196
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Mercury bioremediation by mercury resistance transposon-mediated in situ molecular breeding. Appl Microbiol Biotechnol 2018; 102:3037-3048. [DOI: 10.1007/s00253-018-8847-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 10/17/2022]
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197
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Ranawat P, Rawat S. Metal-tolerant thermophiles: metals as electron donors and acceptors, toxicity, tolerance and industrial applications. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:4105-4133. [PMID: 29238927 DOI: 10.1007/s11356-017-0869-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/28/2017] [Indexed: 06/07/2023]
Abstract
Metal-tolerant thermophiles are inhabitants of a wide range of extreme habitats like solfatara fields, hot springs, mud holes, hydrothermal vents oozing out from metal-rich ores, hypersaline pools and soil crusts enriched with metals and other elements. The ability to withstand adverse environmental conditions, like high temperature, high metal concentration and sometimes high pH in their niche, makes them an interesting subject for understanding mechanisms behind their ability to deal with multiple duress simultaneously. Metals are essential for biological systems, as they participate in biochemistries that cannot be achieved only by organic molecules. However, the excess concentration of metals can disrupt natural biogeochemical processes and can impose toxicity. Thermophiles counteract metal toxicity via their unique cell wall, metabolic factors and enzymes that carry out metal-based redox transformations, metal sequestration by metallothioneins and metallochaperones as well as metal efflux. Thermophilic metal resistance is heterogeneous at both genetic and physiology levels and may be chromosomally, plasmid or transposon encoded with one or more genes being involved. These effective response mechanisms either individually or synergistically make proliferation of thermophiles in metal-rich habitats possibly. This article presents the state of the art and future perspectives of responses of thermophiles to metals at genetic as well as physiological levels.
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Affiliation(s)
- Preeti Ranawat
- Department of Botany and Microbiology, Hemvati Nandan Bahuguna Garhwal University, Srinagar (Garhwal), Uttarakhand, India
| | - Seema Rawat
- School of Life Sciences, Central University of Gujarat, Gandhinagar, Gujarat, India.
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Eklöf K, Bishop K, Bertilsson S, Björn E, Buck M, Skyllberg U, Osman OA, Kronberg RM, Bravo AG. Formation of mercury methylation hotspots as a consequence of forestry operations. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 613-614:1069-1078. [PMID: 28950669 DOI: 10.1016/j.scitotenv.2017.09.151] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 05/16/2023]
Abstract
Earlier studies have shown that boreal forest logging can increase the concentration and export of methylmercury (MeHg) in stream runoff. Here we test whether forestry operations create soil environments of high MeHg net formation associated with distinct microbial communities. Furthermore, we test the hypothesis that Hg methylation hotspots are more prone to form after stump harvest than stem-only harvest, because of more severe soil compaction and soil disturbance. Concentrations of MeHg, percent MeHg of total Hg (THg), and bacterial community composition were determined at 200 soil sampling positions distributed across eight catchments. Each catchment was either stem-only harvested (n=3), stem- and stump-harvested (n=2) or left undisturbed (n=3). In support of our hypothesis, higher MeHg to THg ratios was observed in one of the stump-harvested catchments. While the effects of natural variation could not be ruled out, we noted that most of the highest % MeHg was observed in water-filled cavities created by stump removal or driving damage. This catchment also featured the highest bacterial diversity and highest relative abundance of bacterial families known to include Hg methylators. We propose that water-logged and disturbed soil environments associated with stump harvest can favor methylating microorganisms, which also enhance MeHg formation.
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Affiliation(s)
- Karin Eklöf
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden.
| | - Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Stefan Bertilsson
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, SE-75236 Uppsala, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Moritz Buck
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden; National Bioinformatics Infrastructure Sweden, Uppsala SE-75236, Sweden
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Omneya A Osman
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, SE-75236 Uppsala, Sweden
| | - Rose-Marie Kronberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Andrea G Bravo
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, SE-75236 Uppsala, Sweden
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199
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Mechirackal Balan B, Shini S, Krishnan KP, Mohan M. Mercury tolerance and biosorption in bacteria isolated from Ny-Ålesund, Svalbard, Arctic. J Basic Microbiol 2018; 58:286-295. [DOI: 10.1002/jobm.201700496] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/23/2017] [Accepted: 01/12/2018] [Indexed: 01/01/2023]
Affiliation(s)
| | - Sruthy Shini
- School of Environmental Sciences; Mahatma Gandhi University; Kottayam Kerala India
| | | | - Mahesh Mohan
- School of Environmental Sciences; Mahatma Gandhi University; Kottayam Kerala India
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200
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Willis CE, Kirk JL, St Louis VL, Lehnherr I, Ariya PA, Rangel-Alvarado RB. Sources of Methylmercury to Snowpacks of the Alberta Oil Sands Region: A Study of In Situ Methylation and Particulates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:531-540. [PMID: 29198105 DOI: 10.1021/acs.est.7b04096] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Snowpacks in the Alberta Oil Sands Region (AOSR) of Canada contain elevated loadings of methylmercury (MeHg; a neurotoxin that biomagnifies through foodwebs) due to oil sands related activities. At sites ranging from 0 to 134 km from the major AOSR upgrading facilities, we examined sources of MeHg by quantifying potential rates of MeHg production in snowpacks and melted snow using mercury stable isotope tracer experiments, as well as quantifying concentrations of MeHg on particles in snowpacks (pMeHg). At four sites, methylation rate constants were low in snowpacks (km = 0.001-0.004 d-1) and nondetectable in melted snow, except at one site (km = 0.0007 d-1). The ratio of methylation to demethylation varied between 0.3 and 1.5, suggesting that the two processes are in balance and that in situ production is unlikely an important net source of MeHg to AOSR snowpacks. pMeHg concentrations increased linearly with distance from the upgraders (R2 = 0.71, p < 0.0001); however, snowpack total particle and pMeHg loadings decreased exponentially over this same distance (R2 = 0.49, p = 0.0002; R2 = 0.56, p < 0.0001). Thus, at near-field sites, total MeHg loadings in snowpacks were high due to high particle loadings, even though particles originating from industrial activities were not MeHg rich compared to those at remote sites. More research is required to identify the industrial sources of snowpack particles in the AOSR.
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Affiliation(s)
- Chelsea E Willis
- Department of Biological Sciences, University of Alberta , Edmonton, Alberta T6G 2E9, Canada
| | - Jane L Kirk
- Aquatic Contaminants Research Division , Environment and Climate Change Canada, Burlington, Ontario L7S 1A1, Canada
| | - Vincent L St Louis
- Department of Biological Sciences, University of Alberta , Edmonton, Alberta T6G 2E9, Canada
| | - Igor Lehnherr
- Department of Geography, University of Toronto Mississauga , Mississauga, Ontario L5L 1C6, Canada
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